Three threat groups are exploiting two Cisco FMC flaws to steal credentials, gain root access and deploy Qilin ransomware.

Cisco Talos says three separate threat groups are exploiting two recently patched Secure Firewall Management Center (FMC) flaws. The main target is CVE-2026-20079, a critical authentication bypass that lets unauthenticated attackers remotely bypass security controls, run scripts and potentially gain root access. Attackers also exploit CVE-2026-20316 to access sensitive data through a low-privilege account. The second flaw can be chained with other FMC vulnerabilities to increase privileges.

Cisco linked the attacks to ransomware operations, including Qilin, as well as state-sponsored activity.

“Talos’ analysis illustrates three clusters of post-compromise activity on FMC instances associated with state-sponsored and crimeware threat actors, as described below.” reads the advisory. “The first cluster which we track as UAT-12197, involves the exploitation of CVE-2026-20079, leading to the deployment of web shells, a Java Archive (JAR)-based command executor, and credential exfiltration.”

Talos identified three attack clusters targeting Cisco Secure Firewall Management Center (FMC). The first cluster deploys JSP-based web shells and custom command executors into Tomcat webroot directories to query internal databases and harvest user authentication data and credentials.

“This cluster of activity involved the successful exploitation of CVE-2026-20079 and the subsequent placement of a malicious web shell in the CSM Tomcat webroot directory.” reads the report. “The web shell is JSP-based and Base64 decodes a parameter labelled “F6C1F0E7”, consisting of the class name to load in the JAVA process:”

The second cluster, attributed to the advanced persistent threat actor UAT-11823 with tooling overlapping Sandworm, establishes Netcat reverse shells, harvests device configurations, and installs the modular ELF malware “Cyclops Blink” for persistent access, DNS over HTTPS resolution, and packet sniffing.

“The threat actor obtained initial access to compromised systems by either exploiting CVE-2026-20079 or via static credentials.” Talos states. “After obtaining access, UAT-11823 subsequently updated the “license.tmp” file on disk (using Makeself) with a malicious copy to establish a Netcat-based reverse shell to their own command-and-control (C2) server:”

The third cluster involves Qilin ransomware operators (UAT-11988) who use static credentials for initial access, perform extensive domain reconnaissance, deploy SOCKS proxies and reverse-SSH tunnels, and execute AV killers before deploying ransomware.

“Once extensive reconnaissance was completed, the threat actor attempted to establish persistent network access into the victim organization using a Python SOCKS5 proxy (socks5.py) and a reverse-SSH tunnel from the FMC back to the attacker’s own remote host. The following ports were forwarded: LDPA (389), LDAPS (636), Kerberos (88), SMB (445), NETBIOS (135), and WinRM (5985).” concludes the report. “The threat actor conducted extensive probing of endpoints in the victim’s environment, deployed open-source tooling such as impacket, Invoke-TheHash, and custom-made AV killers — all followed by the deployment of the Qilin ransomware on selected endpoints.”

Cisco strongly urges customers to immediately apply released hotfixes and update detection rules using the provided Snort SIDs while awaiting upcoming comprehensive security hardening updates.

CISA added CVE-2026-20079 to its KEV catalog, requiring U.S. federal agencies to patch it by September 12, 2026. CVE-2026-20316 was added in late July.

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Pierluigi Paganini

(SecurityAffairs – hacking, Cisco FMC)

Cisco has released security updates for an actively exploited zero-day vulnerability, CVE-2026-20316, affecting Cisco Secure FMC (Secure Firewall Management Center) software. The flaw, disclosed on July 29, 2026, allows a remote, unauthenticated attacker to log in to vulnerable systems using a built-in low-privilege account and access sensitive data.  Cisco said it detected active exploitation in July and has published indicators of compromise (IoCs) to help organizations identify potential attacks. The vulnerability was reported by Jimi Sebree of Horizon3.ai. 

Static credentials expose Cisco Secure FMC systems 

Cisco describes CVE-2026-20316 as a static credential vulnerability (CWE-259) caused by the presence of hardcoded credentials for a low-privilege account in the web interface of Cisco Secure FMC. A successful attack enables unauthorized access to sensitive information available to that account. Although the flaw carries a CVSS 3.1 base score of 5.3, Cisco assigned it a High Security Impact Rating because it can be chained with other Cisco Secure FMC vulnerabilities to achieve privilege escalation.  According to Cisco's advisory, "If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced." However, the company stressed that no workarounds are available and urged customers to install the released hot fixes.  The vulnerability affects Cisco Secure FMC software regardless of device configuration. Cisco confirmed that Cloud-Delivered FMC (cdFMC), Firewall Device Manager (FDM), Secure Firewall ASA Software, Secure Firewall Threat Defense (FTD) Software, and Security Cloud Control (formerly Defense Orchestrator) are not affected. 

Indicators of compromise and available hot fixes 

Cisco provided IoCs to help identify potential exploitation of CVE-2026-20316. Administrators are advised to run cat /var/log/messages | grep license in expert mode. Log entries referencing /var/tmp/license.tmp may indicate compromise. If exploitation is suspected, Cisco recommends contacting its Technical Assistance Center (TAC) and rotating all user credentials, cryptographic keys, and certificates on the affected Cisco Secure FMC device because exploitation has been ongoing.  The company released hot fixes for software releases 7.0, 7.2, 7.4, 7.6, 7.7, and 10.0. Cisco emphasized that upgrading to the fixed software is the only complete remediation for CVE-2026-20316. 

CISA adds CVE-2026-20316 to KEV catalog 

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2026-20316 to its Known Exploited Vulnerabilities (KEV) catalog on July 29, directing federal civilian agencies to remediate the issue by August 1. While Cisco acknowledged ongoing exploitation and published IoCs, it has not disclosed details about the attacks observed in the wild, and no public reports describing the campaigns have emerged. Horizon3.ai has also not released technical details about the vulnerability. Cisco additionally updated its advisory for CVE-2026-20079, a critical Cisco Secure FMC vulnerability originally patched in March. The latest disclosure follows several recent instances in which Cisco identified active exploitation targeting other products, including Catalyst SD-WAN Manager and Unified Communications Manager, highlighting the continued focus on securing enterprise networking infrastructure.