---
id: "CVE-2026-76490"
kind: "vulnerability"
aliases: ["CVE-2026-76490"]
title: "Cisco Expressway: out-of-bounds write flaws may let attackers run code"
severity: "high"
cvss: 8.6
epss: 0.00346
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["cisco-expressway", "infrastructure", "self-hosted", "video-conferencing"]
not_affected_if: ["unknown"]
published_at: "2026-10-21T17:19:08+00:00"
first_seen_at: "2026-10-23T21:57:29+00:00"
updated_at: "2026-10-24T13:15:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-76490", "first_seen_at": "2026-10-23T21:57:29+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-76490", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# Cisco Expressway: out-of-bounds write flaws may let attackers run code

Cisco Expressway Series video gateways contain multiple out-of-bounds write flaws found in an internal security review, classified as CWE-787. The sources do not say what an attacker can do after triggering them, and NVD rates the issue 8.6 (high).

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

Check the installed Expressway software version in the admin interface under Status or System information and compare it with the fixed releases in Cisco's advisory.

## Fix

Upgrade Cisco Expressway to a fixed software release named in Cisco's security advisory; the release number is unknown from these sources.

## Timeline

- 2026-10-23T21:57:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-76490
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-76490

## From the sources

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-2026-76490 are related to issues concerning out-of-bounds writes that are grouped under the Common Weakness Enumeration (CWE) Base CWE-787.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_