CVE-2026-76466

CRITICAL 9.8

Published 2026-10-21 · Last modified 2026-10-22

A vulnerability in the database service feature of Cisco Expressway Series could allow an unauthenticated, remote attacker with network access to a Cisco Expressway device to execute arbitrary operating system commands as root. This vulnerability is due to the use of persistent cookies. Additionally, there is insufficient validation of client certificates when the TLS Verify Mode is set to Enabled for clustering, which means that client certificates are not validated. An attacker with possession of the cookies could exploit this vulnerability by connecting to the database service and invoking specific remote procedure call (RPC) commands. A successful exploit could allow the attacker to execute arbitrary commands as root on the underlying operating system of an affected device. Note: Cisco Expressway Series refers to Cisco Expressway Core (Expressway-C) devices and Cisco Expressway Edge (Expressway-E) devices.

ELEVATED IMPACT

Severe if exploited (CVSS 9.8), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 36th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

9.8CVSS 3.1 · CRITICAL

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

What an attacker needs

✓Access: Reachable over the network — no local access needed
✓Privileges: No account or privileges required
✓User interaction: No user interaction needed
✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Data snapshot: 2026-10-26T13:52:32.101Z