Unit 42 uncovers escalating Kubernetes attacks, detailing how threat actors exploit identities and critical vulnerabilities to compromise cloud environments.
The post Understanding Current Threats to Kubernetes Environments appeared first on Unit 42.
The fourth quarter of 2025 went down as one of the most intense periods on record for high-profile, critical vulnerability disclosures, hitting popular libraries and mainstream applications. Several of these vulnerabilities were picked up by attackers and exploited in the wild almost immediately.
In this report, we dive into the statistics on published vulnerabilities and exploits, as well as the known vulnerabilities leveraged with popular C2 frameworks throughout Q4 2025.
This section contains statistics on registered vulnerabilities. The data is taken from cve.org.
Let’s take a look at the number of registered CVEs for each month over the last five years, up to and including the end of 2025. As predicted in our last report, Q4 saw a higher number of registered vulnerabilities than the same period in 2024, and the year-end totals also cleared the bar set the previous year.
Total published vulnerabilities by month from 2021 through 2025 (download)
Now, let’s look at the number of new critical vulnerabilities (CVSS > 8.9) for that same period.
Total number of published critical vulnerabilities by month from 2021 to 2025< (download)
The graph shows that the volume of critical vulnerabilities remains quite substantial; however, in the second half of the year, we saw those numbers dip back down to levels seen in 2023. This was due to vulnerability churn: a handful of published security issues were revoked. The widespread adoption of secure development practices and the move toward safer languages also pushed those numbers down, though even that couldn’t stop the overall flood of vulnerabilities.
This section contains statistics on the use of exploits in Q4 2025. The data is based on open sources and our telemetry.
In Q4 2025, the most prevalent exploits targeted the exact same vulnerabilities that dominated the threat landscape throughout the rest of the year. These were exploits targeting Microsoft Office products with unpatched security flaws.
Kaspersky solutions detected the most exploits on the Windows platform for the following vulnerabilities:
The list has remained unchanged for years.
We also see that attackers continue to adapt exploits for directory traversal vulnerabilities (CWE-35) when unpacking archives in WinRAR. They are being heavily leveraged to gain initial access via malicious archives on the Windows operating system:
As in the previous quarter, we see a rise in the use of archiver exploits, with fresh vulnerabilities increasingly appearing in attacks.
Below are the exploit detection trends for Windows users over the last two years.
Dynamics of the number of Windows users encountering exploits, Q1 2024 – Q4 2025. The number of users who encountered exploits in Q1 2024 is taken as 100% (download)
The vulnerabilities listed here can be used to gain initial access to a vulnerable system. This highlights the critical importance of timely security updates for all affected software.
On Linux-based devices, the most frequently detected exploits targeted the following vulnerabilities:
Dynamics of the number of Linux users encountering exploits, Q1 2024 – Q4 2025. The number of users who encountered exploits in Q1 2024 is taken as 100% (download)
We are seeing a massive surge in Linux-based exploit attempts: in Q4, the number of affected users doubled compared to Q3. Our statistics show that the final quarter of the year accounted for more than half of all Linux exploit attacks recorded for the entire year. This surge is primarily driven by the rapidly growing number of Linux-based consumer devices. This trend naturally attracts the attention of threat actors, making the installation of security patches critically important.
The distribution of published exploits by software type in Q4 2025 largely mirrors the patterns observed in the previous quarter. The majority of exploits we investigate through our monitoring of public research, news, and PoCs continue to target vulnerabilities within operating systems.
Distribution of published exploits by platform, Q1 2025 (download)
Distribution of published exploits by platform, Q2 2025 (download)
Distribution of published exploits by platform, Q3 2025 (download)
Distribution of published exploits by platform, Q4 2025 (download)
In Q4 2025, no public exploits for Microsoft Office products emerged; the bulk of the vulnerabilities were issues discovered in system components. When calculating our statistics, we placed these in the OS category.
We analyzed which vulnerabilities were utilized in APT attacks during Q4 2025. The following rankings draw on our telemetry, research, and open-source data.
TOP 10 vulnerabilities exploited in APT attacks, Q4 2025 (download)
In Q4 2025, APT attacks most frequently exploited fresh vulnerabilities published within the last six months. We believe that these CVEs will remain favorites among attackers for a long time, as fixing them may require significant structural changes to the vulnerable applications or the user’s system. Often, replacing or updating the affected components requires a significant amount of resources. Consequently, the probability of an attack through such vulnerabilities may persist. Some of these new vulnerabilities are likely to become frequent tools for lateral movement within user infrastructure, as the corresponding security flaws have been discovered in network services that are accessible without authentication. This heavy exploitation of very recently registered vulnerabilities highlights the ability of threat actors to rapidly implement new techniques and adapt old ones for their attacks. Therefore, we strongly recommend applying the security patches provided by vendors.
In this section, we will look at the most popular C2 frameworks used by threat actors and analyze the vulnerabilities whose exploits interacted with C2 agents in APT attacks.
The chart below shows the frequency of known C2 framework usage in attacks against users during Q4 2025, according to open sources.
TOP 10 C2 frameworks used by APTs to compromise user systems in Q4 2025 (download)
Despite the significant footprints it can leave when used in its default configuration, Sliver continues to hold the top spot among the most common C2 frameworks in our Q4 2025 analysis. Mythic and Havoc were second and third, respectively. After reviewing open sources and analyzing malicious C2 agent samples that contained exploits, we found that the following vulnerabilities were used in APT attacks involving the C2 frameworks mentioned above:
The set of vulnerabilities described above suggests that attackers have been using them for initial access and early-stage maneuvers in vulnerable systems to create a springboard for deploying a C2 agent. The list of vulnerabilities includes both zero-days and well-known, established security issues.
This section highlights the most noteworthy vulnerabilities that were publicly disclosed in Q4 2025 and have a publicly available description.
We typically describe vulnerabilities affecting a specific application. CVE-2025-55182 stood out as an exception, as it was discovered in React, a library primarily used for building web applications. This means that exploiting the vulnerability could potentially disrupt a vast number of applications that rely on the library. The vulnerability itself lies in the interaction mechanism between the client and server components, which is built on sending serialized objects. If an attacker sends serialized data containing malicious functionality, they can execute JavaScript commands directly on the server, bypassing all client-side request validation. Technical details about this vulnerability and an example of how Kaspersky solutions detect it can be found in our article.
This vulnerability represents a data-handling flaw that occurs when retrieving information from a remote server: when executing the curl or Invoke-WebRequest command, Windows launches Internet Explorer in the background. This can lead to a cross-site scripting (XSS) attack.
This vulnerability reinforces the trend of exploiting security flaws found in file archivers. The core of CVE-2025-11001 lies in the incorrect handling of symbolic links. An attacker can craft an archive so that when it is extracted into an arbitrary directory, its contents end up in the location pointed to by a symbolic link. The likelihood of exploiting this vulnerability is significantly reduced because utilizing such functionality requires the user opening the archive to possess system administrator privileges.
This vulnerability was associated with a wave of misleading news reports claiming it was being used in real-world attacks against end users. This misconception stemmed from an error in the security bulletin.
The year 2025 saw a surge in high-profile vulnerabilities, several of which were significant enough to earn a unique nickname. This was the case with CVE-2025-49844, also known as RediShell, which was unveiled during a hacking competition. This vulnerability is a use-after-free issue related to how the load command functions within Lua interpreter scripts. To execute the attack, an attacker needs to prepare a malicious script and load it into the interpreter.
As with any named vulnerability, RediShell was immediately weaponized by threat actors and spammers, albeit in a somewhat unconventional manner. Because technical details were initially scarce following its disclosure, the internet was flooded with fake PoC exploits and scanners claiming to test for the vulnerability. In the best-case scenario, these tools were non-functional; in the worst, they infected the system. Notably, these fraudulent projects were frequently generated using LLMs. They followed a standardized template and often cross-referenced source code from other identical fake repositories.
Driver vulnerabilities are often discovered in legitimate third-party applications that have been part of the official OS distribution for a long time. Thus, CVE-2025-24990 has existed within code shipped by Microsoft throughout nearly the entire history of Windows. The vulnerable driver has been shipped since at least Windows 7 as a third-party driver for Agere Modem. According to Microsoft, this driver is no longer supported and, following the discovery of the flaw, was removed from the OS distribution entirely.
The vulnerability itself is straightforward: insecure handling of IOCTL codes leading to a null pointer dereference. Successful exploitation can lead to arbitrary command execution or a system crash resulting in a blue screen of death (BSOD) on modern systems.
CVE-2025-59287 represents a textbook case of insecure deserialization. Exploitation is possible without any form of authentication; due to its ease of use, this vulnerability rapidly gained traction among threat actors. Technical details and detection methodologies for our product suite have been covered in our previous advisories.
In Q4 2025, the rate of vulnerability registration has shown no signs of slowing down. Consequently, consistent monitoring and the timely application of security patches have become more critical than ever. To ensure resilient defense, it is vital to regularly assess and remediate known vulnerabilities while implementing technology designed to mitigate the impact of potential exploits.
Continuous monitoring of infrastructure, including the network perimeter, allows for the timely identification of threats and prevents them from escalating. Effective security also demands tracking the current threat landscape and applying preventative measures to minimize risks associated with system flaws. Kaspersky Next serves as a reliable partner in this process, providing real-time identification and detailed mapping of vulnerabilities within the environment.
Securing the workplace remains a top priority. Protecting corporate devices requires the adoption of solutions capable of blocking malware and preventing it from spreading. Beyond basic measures, organizations should implement adaptive systems that allow for the rapid deployment of security updates and the automation of patch management workflows.
On December 4, 2025, researchers published details on the critical vulnerability CVE-2025-55182, which received a CVSS score of 10.0. It has been unofficially dubbed React2Shell, as it affects React Server Components (RSC) functionality used in web applications built with the React library. RSC speeds up UI rendering by distributing tasks between the client and the server. The flaw is categorized as CWE-502 (Deserialization of Untrusted Data). It allows an attacker to execute commands, as well as read and write files in directories accessible to the web application, with the server process privileges.
Almost immediately after the exploit was published, our honeypots began registering attempts to leverage CVE-2025-55182. This post analyzes the attack patterns, the malware that threat actors are attempting to deliver to vulnerable devices, and shares recommendations for risk mitigation.
React applications are built on a component-based model. This means each part of the application or framework should operate independently and offer other components clear, simple methods for interaction. While this approach allows for flexible development and feature addition, it can require users to download large amounts of data, leading to inconsistent performance across devices. This is the challenge React Server Components were designed to address.
The vulnerability was found within the Server Actions component of RSC. To reach the vulnerable function, the attacker just needs to send a POST request to the server containing a serialized data payload for execution. Part of the functionality of the handler that allows for unsafe deserialization is illustrated below:
A comparison of the vulnerable (left) and patched (right) functions
As the vulnerability is rather simple to exploit, the attackers quickly added it to their arsenal. The initial exploitation attempts were registered by Kaspersky honeypots on December 5. By Monday, December 8, the number of attempts had increased significantly and continues to rise.
The number of CVE-2025-55182 attacks targeting Kaspersky honeypots, by day (download)
Attackers first probe their target to ensure it is not a honeypot: they run whoami, perform multiplication in bash, or compute MD5 or Base64 hashes of random strings to verify their code can execute on the targeted machine.
In most cases, they then attempt to download malicious files using command-line web clients like wget or curl. Additionally, some attackers deliver a PowerShell-based Windows payload that installs XMRig, a popular Monero crypto miner.
CVE-2025-55182 was quickly weaponized by numerous malware campaigns, ranging from classic Mirai/Gafgyt variants to crypto miners and the RondoDox botnet. Upon infecting a system, RondoDox wastes no time, its loader script immediately moving to eliminate competitors:
Beyond checking hardcoded paths, RondoDox also neutralizes AppArmor and SELinux security modules and employs more sophisticated methods to find and terminate processes with ELF files removed for disguise.
Only after completing these steps does the script download and execute the main payload by sequentially trying three different loaders: wget, curl, and wget from BusyBox. It also iterates through 18 different malware builds for various CPU architectures, enabling it to infect both IoT devices and standard x86_64 Linux servers.
In some attacks, instead of deploying malware, the adversary attempted to steal credentials for Git and cloud environments. A successful breach could lead to cloud infrastructure compromise, software supply chain attacks, and other severe consequences.
We strongly recommend updating the relevant packages by applying patches released by the developers of the corresponding modules and bundles.
Vulnerable versions of React Server Components:
Bundles and modules confirmed as using React Server Components:
To prevent exploitation while patches are being deployed, consider blocking all POST requests containing the following keywords in parameters or the request body:
Due to the ease of exploitation and the public availability of a working PoC, threat actors have rapidly adopted CVE-2025-55182. It is highly likely that attacks will continue to grow in the near term.
We recommend immediately updating React to the latest patched version, scanning vulnerable hosts for signs of malware, and changing any credentials stored on them.
Malware URLs
hxxp://172.237.55.180/b
hxxp://172.237.55.180/c
hxxp://176.117.107.154/bot
hxxp://193.34.213.150/nuts/bolts
hxxp://193.34.213.150/nuts/x86
hxxp://23.132.164.54/bot
hxxp://31.56.27.76/n2/x86
hxxp://31.56.27.97/scripts/4thepool_miner[.]sh
hxxp://41.231.37.153/rondo[.]aqu[.]sh
hxxp://41.231.37.153/rondo[.]arc700
hxxp://41.231.37.153/rondo[.]armeb
hxxp://41.231.37.153/rondo[.]armebhf
hxxp://41.231.37.153/rondo[.]armv4l
hxxp://41.231.37.153/rondo[.]armv5l
hxxp://41.231.37.153/rondo[.]armv6l
hxxp://41.231.37.153/rondo[.]armv7l
hxxp://41.231.37.153/rondo[.]i486
hxxp://41.231.37.153/rondo[.]i586
hxxp://41.231.37.153/rondo[.]i686
hxxp://41.231.37.153/rondo[.]m68k
hxxp://41.231.37.153/rondo[.]mips
hxxp://41.231.37.153/rondo[.]mipsel
hxxp://41.231.37.153/rondo[.]powerpc
hxxp://41.231.37.153/rondo[.]powerpc-440fp
hxxp://41.231.37.153/rondo[.]sh4
hxxp://41.231.37.153/rondo[.]sparc
hxxp://41.231.37.153/rondo[.]x86_64
hxxp://51.81.104.115/nuts/bolts
hxxp://51.81.104.115/nuts/x86
hxxp://51.91.77.94:13339/termite/51.91.77.94:13337
hxxp://59.7.217.245:7070/app2
hxxp://59.7.217.245:7070/c[.]sh
hxxp://68.142.129.4:8277/download/c[.]sh
hxxp://89.144.31.18/nuts/bolts
hxxp://89.144.31.18/nuts/x86
hxxp://gfxnick.emerald.usbx[.]me/bot
hxxp://meomeoli.mooo[.]com:8820/CLoadPXP/lix.exe?pass=PXPa9682775lckbitXPRopGIXPIL
hxxps://api.hellknight[.]xyz/js
hxxps://gist.githubusercontent[.]com/demonic-agents/39e943f4de855e2aef12f34324cbf150/raw/e767e1cef1c35738689ba4df9c6f7f29a6afba1a/setup_c3pool_miner[.]sh
MD5 hashes
0450fe19cfb91660e9874c0ce7a121e0
3ba4d5e0cf0557f03ee5a97a2de56511
622f904bb82c8118da2966a957526a2b
791f123b3aaff1b92873bd4b7a969387
c6381ebf8f0349b8d47c5e623bbcef6b
e82057e481a2d07b177d9d94463a7441
A critical remote code execution (RCE) vulnerability, dubbed ‘React2Shell’, affecting React Server Components (RSC) and Next.js, is allowing unauthenticated attackers to perform server-side code attacks via malicious HTTP requests.
Discovered by Lachlan Davidson, the flaw stems from insecure deserialization in the RSC ‘Flight’ protocol and impacts packages including react-server-dom-webpack, react-server-dom-parcel, and react-server-dom-turbopack. Exploitation is highly reliable, even in default deployments, and a single request can compromise the full Node.js process. The flaw is being tracked as CVE-2025-55182. Originally tagged as a CVE for Next.js, NIST subsequently rejected CVE-2025-66478, as it is a duplicate of CVE-2025-55182.
This blog post includes the critical, immediate actions recommended to secure your environment, new and existing Platform Detection Rules designed to defend against this vulnerability, and information on how SentinelOne Offensive Security Engine, a core component of the Singularity
Cloud Security solution, allows our customers to quickly identify potentially vulnerable workloads.
On December 3, 2025, the React and Next.js teams disclosed two related vulnerabilities in the React Server Components (RSC) Flight protocol: CVE-2025-55182 (React) and CVE-2025-66478 (Next.js), with the latter CVE now marked by NIST as a duplicate.
Both enable unauthenticated RCE, impacting applications that use RSC directly or through popular frameworks such as Next.js. These vulnerabilities are rated critical (CVSS 10.0) because exploitation requires only a crafted HTTP request. No authentication, user action, or developer-added server code is needed for an attacker to gain control of the underlying Node.js process.
The vulnerability exists because RSC payloads are deserialized without proper validation, exposing server functions to attacker-controlled inputs. Since many modern frameworks enable RSC as part of their default build, some teams may be exposed without being aware that server-side RSC logic is active in their environment.
Security testing currently shows:
EntrarNext.js app created with create-next-app and deployed with no code changesNode.js process compromiseSecurity researchers warn that cloud environments and server-side applications using default React or Next.js builds are particularly at risk. Exploitation could allow attackers to gain full control over servers, access sensitive data, and compromise application functionality. Reports have already emerged of China-nexus threat groups “racing to weaponize” the flaw.
Fixes are available in React 19.0, 19.1.0, 19.1.1, and 19.2.0, and Next.js 5.x, Next.js 16.x, Next.js 14.3.0-canary.77 and later canary releases. Administrators are urged to audit environments and update affected packages immediately.
Companies are advised to review deployments, restrict unnecessary server-side exposure, and monitor logs for anomalous RSC requests. Securing default configurations, validating deserialized input, and maintaining a regular patch management schedule can prevent attackers from exploiting framework-level vulnerabilities in production applications.
Next.js and other RSC-enabled frameworks as listed above. Ensure the latest framework and bundler releases are installed so they ship the patched React server bundles.SentinelOne’s Offensive Security Engine (OSE), core component of its Singularity Cloud Security solution, proactively distinguishes between theoretical risks and actual threats by simulating an attacker’s methodology. Rather than relying solely on static scans that flag every potential misconfiguration or vulnerability, this engine automatically conducts safe, harmless simulations against your cloud infrastructure to validate exploitability.
This approach delivers differentiated outcomes by radically reducing alert fatigue and focusing security teams on immediate, confirmed dangers. By providing concrete evidence of exploitability—such as screenshots or code snippets of the successful simulation—it eliminates the need for manual validation and “red teaming” of every alert. Shift from chasing hypothetical vulnerabilities to remediating verified attack vectors, ensuring resources are always deployed against the risks that pose a genuine threat to their environment.
In response to this vulnerability, SentinelOne released a new OSE plugin which can verify exploitability of these vulnerabilities for publicly accessible workloads using a defanged (i.e., harmless) HTTP payload.
SentinelOne customers can quickly identify potentially vulnerable workloads using the Misconfigurations page in the SentinelOne Console.
Search for:
React & Next.js (React Server Components) Versions 19.0.0–19.2.0 Vulnerable to Pre-Authentication Remote Code Execution via Unsafe Deserialization (CVE-2025-55182)
This highlights Node.js workloads that are exposing RSC-related server function endpoints. Once identified, affected assets can be patched or temporarily isolated. SentinelOne CWS also detects suspicious Node.js behaviors associated with exploitation attempts, including downloaders and reverse shells, and provides Live Security Updates to maintain protection as new detections are deployed.
It identifies verified exploitable paths on your publicly exposed assets, confirming which systems are truly at risk. By validating exploitability rather than simply flagging theoretical vulnerabilities, Singularity Cloud Security minimizes noise and provides concrete evidence so security teams can focus on what matters.
The Wayfinder Threat Hunting team is proactively hunting for this emerging threat by leveraging comprehensive threat intelligence. This includes, but is not limited to, indicators and tradecraft associated with known active groups such as Earth Lamia and Jackpot Panda.
Our current operational coverage includes:
Notification & Response All identified true positive findings will generate alerts within the console for the affected sites. For clients with MDR, the MDR team will actively review these alerts and manage further escalation as required.
SentinelOne’s products provide a variety of detections for potential malicious follow-on reverse shell behaviors and other actions which may follow this exploit. As of December 5, 2025, SentinelOne released new Platform Detection Rules specifically to detect observed in-the-wild exploit activity. We recommend customers apply the latest detection rule, Potential Exploitation via Insecure Deserialization of React Server Components (RSC), urgently to ensure maximum protection.
Additionally, SentinelOne recommends customers verify the following existing rules have also been enabled:
CVE-2025-55182 and CVE-2025-66478 represent critical risks within the React Server Components Flight protocol. Because frameworks like Next.js enable RSC by default, many environments may be exposed even without intentional server-side configuration. Updating React, updating dependent frameworks, and verifying whether RSC endpoints exist in your organization’s workloads are essential steps.
Singularity Cloud Security helps organizations reduce risk by identifying vulnerable workloads, flagging misconfigurations, and detecting malicious Node.js behavior linked to RCE exploitation. This provides immediate visibility and defense while patches are applied.
Learn more about SentinelOne’s Cloud Security portfolio here or book a demo with our expert team today.
Third-Party Trademark Disclaimer:
All third-party product names, logos, and brands mentioned in this publication are the property of their respective owners and are for identification purposes only. Use of these names, logos, and brands does not imply affiliation, endorsement, sponsorship, or association with the third-party.
