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Critical Cisco Expressway RCE Vulnerability Exploit Released

Critical Cisco Expressway RCE Vulnerability Exploit Released

First seen 12 Nov 2026, 11:49 UTC • •
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ThreatCluster AI
ThreatCluster •November 12, 2026 at 11:51 UTC
  • •CVE-2026-76466 allows root command execution via hard-coded credentials.
  • •Public PoC exploit was released on October 27, 2026, increasing risk of exploitation.
  • •Cisco advises immediate patching for affected systems, with no workarounds available.

A proof-of-concept exploit for CVE-2026-76466, a critical remote code execution vulnerability in Cisco Expressway, has been publicly released. This flaw, with a CVSS score of 9.8, allows unauthenticated attackers to execute commands as root on affected systems. The vulnerability exists in the cluster-manager module, where hard-coded credentials can be exploited via the Erlang distribution port (TCP 4372). Cisco's advisory, published on October 21, 2026, states that both Expressway-C and Expressway-E are affected when clustered. The exploit was validated on Expressway-C X15.3.2 in TLS Permissive mode, and no malicious exploitation was confirmed at the time of the advisory. Cisco has urged users to upgrade to fixed releases as no workarounds are available.

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Timeline

2026-10-21
Cisco publishes advisory for CVE-2026-76466
Cisco disclosed a critical RCE vulnerability affecting Expressway systems, urging prompt action.
Gbhackers
2026-10-27
Public PoC exploit released
Researcher Nicolas Krassas posted a proof-of-concept exploit for the critical Cisco vulnerability on GitHub.
Gbhackers

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Common questions

Which Cisco Expressway versions are affected?
Both Expressway-C and Expressway-E are affected when configured in a clustered environment.
What is the attack vector for this vulnerability?
An attacker can exploit the vulnerability by accessing the Erlang distribution port (TCP 4372) with knowledge of hard-coded credentials.
What should organizations do to mitigate this risk?
Organizations must upgrade to the fixed release X15.5.20 or later, as no workarounds are available.