Active exploitation of Cisco Secure Firewall Management Center vulnerabilities
Cisco Talos reports in-the-wild exploitation of critical FMC flaw CVE-2026-20079 by three clusters including a Sandworm-linked APT and Qilin ransomware affiliates.
Cisco Talos is tracking active exploitation of CVE-2026-20079 (CVSS 10.0), an authentication bypass in Cisco Secure Firewall Management Center that lets unauthenticated remote attackers execute scripts and obtain root access, and CVE-2026-20316 (CVSS 5.3), which permits low-privileged logins and can be chained for privilege escalation. Talos identified three post-compromise clusters: UAT-12197 deploying JSP web shells and a JAR command executor for credential theft; UAT-11823, an APT overlapping with Sandworm, deploying a Netcat reverse shell and Cyclops Blink malware; and UAT-11988, assessed as a ransomware operator with TTPs consistent with Qilin affiliates. Hotfixes are available, with a comprehensive hardening release due the week of September 14, 2026.
SharePoint CVE-2026-55040 Comes Under Attack Following Public Exploit
Attackers are actively exploiting critical SharePoint authentication bypass CVE-2026-55040 (CVSS 9.1) days after Rapid7 released a public PoC.
CVE-2026-55040 is a critical authentication bypass (CVSS 9.1) in SharePoint Server Subscription Edition that lets unauthenticated attackers forge JWT tokens and impersonate any user, including administrators. Microsoft patched it in July 2026 Patch Tuesday, but Rapid7 published a technical write-up and Python PoC on GitHub on August 12, and Defused quickly observed attackers running the PoC against SharePoint honeypots. KEVIntel recorded 12 exploitation attempts since July 19, with eight occurring on August 12-13 from IP addresses in Hong Kong, Japan, the Netherlands, Taiwan and the U.S. Admin-level SharePoint access exposes documents and data modification and can serve as a foothold into broader Microsoft 365 infrastructure; unpatched instances should apply the July update immediately.
CVE-2026-34908: Ubiquiti Networks UniFi OS Server access control ...
CVE-2026-34908, a CVSS 10.0 access-control bypass in Ubiquiti UniFi OS, was added to CISA's KEV catalog amid reported active exploitation.
CISA added CVE-2026-34908 to the Known Exploited Vulnerabilities catalog on June 23, 2026, with remediation due June 26 under BOD 26-04 guidance. The CVSS 10.0 improper access control flaw (CWE-284) in Ubiquiti UniFi OS allows unauthorized system changes without authentication. Multiple news reports referenced by the page describe the max-severity UniFi flaws being exploited in attacks, and an official patch is available.
CVE-2026-34486: Apache Software Foundation Apache Tomcat
CISA added CVE-2026-34486, an actively exploited Apache Tomcat EncryptInterceptor bypass enabling unauthenticated deserialization RCE, to its KEV catalog.
CVE-2026-34486 allows bypass of Apache Tomcat's EncryptInterceptor, a flaw introduced by the fix for padding-oracle issue CVE-2026-29146 in Tribes cluster encryption. CISA added the flaw to the Known Exploited Vulnerability catalog on August 4, 2026, alongside actively exploited Langflow and N-central flaws, with remediation required under BOD 26-04 guidance. Official patches and workarounds are available, and reporting notes unauthenticated remote code execution through Java deserialization on the Tribes receiver port 4000.