CVE intelligence

CVE-2026-76466

Vulnerability intelligence

Published Oct 21, 2026Sources checked Oct 21, 2026

9.8CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-76466 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Cisco Security Advisories guidance

Vendor revision: Oct 21, 2026

To remediate the vulnerabilities that were disclosed on October 21, 2026, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories.

Cisco Security Advisories guidance

Vendor revision: Oct 21, 2026

Cisco has released software updates that address this vulnerability.

CISA KEVNot listedBased on the latest collected catalog

EPSSUnavailableNo current score collected

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-76466?

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.

Source: NVD

Official advisory

Configuration and update guidance

Cisco Security Advisories · Updated Oct 21, 2026

Affected products and configuration

This vulnerability affects Cisco Expressway-C and Cisco Expressway-E, both virtual and appliance versions, if they are running a vulnerable release and have the devices configured in a cluster.

For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.

Workarounds and temporary mitigations

There are no workarounds that address this vulnerability.

Fixed software

Cisco considers any workarounds and mitigations (if applicable) to be temporary solutions until an upgrade to a fixed software release is available. To remediate this vulnerability and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.

Fixed Releases

In the following table, the left column lists Cisco software releases. The right column indicates whether a release is affected by the vulnerability that is described in this advisory and the first release that includes the fix for this vulnerability. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.

Cisco Expressway Series Release	First Fixed Release
X14 and earlier	Migrate to a fixed release.
X15.5.3 and earlier	X15.5.20

Note: This fix is also included as part of the broader hardening improvements that are disclosed in the security advisory Cisco Expressway Series Security Hardening Release: October 2026.

The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.

Exploitation status

The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

Read the collected advisory