Is CVE-2026-76491 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-76491 being exploited in the wild.

How severe is CVE-2026-76491?

High severity, with a CVSS score of 7.5, published 21 October 2026.

Which products and versions are affected?

Cisco Expressway Core X14 and earlier, X15.5.3 and earlier; Cisco Expressway Edge X14 and earlier, X15.5.3 and earlier.

Is there a fix for CVE-2026-76491?

Yes: fixed in Expressway X15.5.20 or later; X14 and earlier require migration to a fixed release. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-76491 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-76491?

Check whether you run Cisco Expressway Core or Cisco Expressway Edge at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-76491: Cisco Expressway Series reachable assertions denial of service

CVE-2026-76491 · Severity: high · CVSS 7.5 · Published 2026-10-21

Cisco Expressway Core and Edge devices, which manage video communications and presence services in enterprise networks, contain multiple hardened vulnerabilities discovered in an internal security review. These issues, grouped under assertion handling and other weakness classes, can cause service crashes leading to denial of service affecting video conferencing and collaboration infrastructure. The vulnerabilities are not currently known to be exploited in the wild.

Technologies: Cisco Expressway Core, Cisco Expressway Edge. Vendors: Cisco.

Quick answers

Is CVE-2026-76491 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-76491 being exploited in the wild.
How severe is CVE-2026-76491?: High severity, with a CVSS score of 7.5, published 21 October 2026.
Which products and versions are affected?: Cisco Expressway Core X14 and earlier, X15.5.3 and earlier; Cisco Expressway Edge X14 and earlier, X15.5.3 and earlier.
Is there a fix for CVE-2026-76491?: Yes: fixed in Expressway X15.5.20 or later; X14 and earlier require migration to a fixed release. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-76491 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-76491?: Check whether you run Cisco Expressway Core or Cisco Expressway Edge at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: Expressway X15.5.20 or later; X14 and earlier require migration to a fixed release

Technical details

Multiple vulnerability classes including reachable assertions (CWE-617), null pointer dereferences (CWE-476), and other weaknesses were discovered during internal security testing and AI-assisted code review. The vulnerabilities affect Cisco Expressway-C and Expressway-E devices (both virtual and appliance versions) regardless of configuration, with remote network access vector requiring no authentication or user interaction. Patched releases are available in both X15.5.20 and later versions.

Affected products

Cisco Expressway Core X14 and earlier, X15.5.3 and earlier
Cisco Expressway Edge X14 and earlier, X15.5.3 and earlier

Timeline

2026-10-21: disclosed

References

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

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