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.
Published: 2026-10-21
Score: 7.5 High
EPSS: n/a
KEV: No
Impact: Denial of Service
Action: Patch
AI Analysis

Impact

The vulnerability arises from reachable assertions (CWE‑617). These assertions can become true when the system processes certain input, potentially causing the Expressway services to crash or restart. The primary impact is a denial of service, disrupting user connectivity without affecting data confidentiality or integrity. The description does not indicate any further compromise beyond availability.

Affected Systems

The affected product is Cisco TelePresence Video Communication Server (VCS) Expressway. No specific version information is provided in the CVE data.

Risk and Exploitability

With a CVSS score of 7.5, the vulnerability poses a high risk. The EPSS score is not available, and the vulnerability is not listed in CISA’s KEV catalog. While the attack vector is not explicitly detailed, the reachable assertion issue suggests that an attacker could trigger the denial of service by sending specially crafted requests or inputs to the Expressway service. The lack of a public exploit does not eliminate the threat; the high severity and the nature of the flaw warrant timely remediation.

Generated by OpenCVE AI on October 21, 2026 at 21:06 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Apply the Cisco Expressway Series Software Hardening Release: October 2026 to all affected VCS Expressway servers.
  • Restart the Expressway services to load the updated binaries and ensure the fixes are active.
  • Monitor service availability and system logs for any recurrence of the denial of service condition.

Generated by OpenCVE AI on October 21, 2026 at 21:06 UTC.

Tracking

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Advisories

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History

Wed, 21 Oct 2026 17:15:00 +0000

Type Values Removed Values Added
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.
Title Cisco Expressway Series Software Hardening Release: October 2026 - Denial of Service Vulnerabilities
Weaknesses CWE-617
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: cisco

Published:

Updated: 2026-10-21T16:17:04.407Z

Reserved: 2026-08-19T12:02:03.640Z

Link: CVE-2026-76491

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-21T17:19:08.480

Modified: 2026-10-21T18:54:37.403

Link: CVE-2026-76491

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-21T21:15:16Z

Weaknesses