---
title: "CVE-2026-76491: Cisco Expressway Series - Denial of Service"
description: "Cisco Expressway Series contains reachable assertion vulnerabilities caused by internal logic errors, letting attackers potentially disrupt normal operation, exploit requires crafted input triggering assertions."
url: https://panop.io/threat-heartbeat/CVE-2026-76491/
---

# CVE-2026-76491 Cisco Expressway Series - Denial of Service

Cisco Expressway Series contains reachable assertion vulnerabilities caused by internal logic errors, letting attackers potentially disrupt normal operation, exploit requires crafted input triggering assertions.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-76491)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Published

21 October 2026

Updated

22 October 2026

Weakness

[CWE-617](https://cwe.mitre.org/data/definitions/617.html)

## Vendor fix

Update to the latest Cisco Expressway Series software version with security hardening.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-76491](https://nvd.nist.gov/vuln/detail/CVE-2026-76491)
- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-exwy-hardening-FhcqBVcs](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-exwy-hardening-FhcqBVcs)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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