CVE intelligence

CVE-2026-76491

Vulnerability intelligence

Published Oct 21, 2026Sources checked Oct 21, 2026

7.5HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-76491 and is rated High severity with a CVSS score of 7.5. 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

To assist customers in patching and streamline the disclosure process, Cisco has grouped these issues by their underlying vulnerability class - Common Weakness Enumeration (CWE) - and assigned a single Common Vulnerabilities and Exposures identifier (CVE ID) to each CWE grouping.

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-2026-76491?

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Expressway Series software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities.

The vulnerabilities tracked by CVE-2026-76491 are related to issues concerning reachable assertions that are grouped under the Common Weakness Enumeration (CWE) Base CWE-617.

Source: NVD

Official advisory

Configuration and update guidance

Cisco Security Advisories · Updated Oct 21, 2026

Affected products and configuration

These vulnerabilities affect Cisco Expressway-C and Cisco Expressway-E, both virtual and appliance versions, regardless of device configuration.

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 these vulnerabilities.

Fixed software

To remediate these vulnerabilities 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 vulnerabilities that are described in this advisory and the first release that includes the fix for these vulnerabilities. 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

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 vulnerabilities that are described in this advisory.

Read the collected advisory