# CVE-2026-76466: Cisco Expressway Series Remote Code Execution Vulnerability


- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 21 Oct 2026
- **Updated:** 22 Oct 2026
- **Also known as:** GHSA-p2jr-qv63-hjch

## What is CVE-2026-76466?

CVE-2026-76466 is a critical vulnerability in Cisco TelePresence Video Communication Server (VCS) Expressway, published on 21 Oct 2026. 

### Official description

A vulnerability in the database service feature of Cisco Expressway Series could allow an unauthenticated, remote attacker with network access to a Cisco Expressway device to execute arbitrary operating system commands as root.

This vulnerability is due to the use of persistent cookies. Additionally, there is insufficient validation of client certificates when the TLS Verify Mode is set to Enabled for clustering, which means that client certificates are not validated. An attacker with possession of the cookies could exploit this vulnerability by connecting to the database service and invoking specific remote procedure call (RPC) commands. A successful exploit could allow the attacker to execute arbitrary commands as root on the underlying operating system of an affected device.
Note: Cisco Expressway Series refers to Cisco Expressway Core (Expressway-C) devices and Cisco Expressway Edge (Expressway-E) devices.

Weakness: CWE-798 (Use of Hard-coded Credentials)

## Which versions are affected by CVE-2026-76466?


## How do I fix CVE-2026-76466?

No fix has been published for CVE-2026-76466 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-76466 being exploited?

There is no known exploitation of CVE-2026-76466 in the wild and no public exploit code.

Public exploit code:

- Offline Python detector for CVE-2026-76466 in Cisco Expressway, using version and clustering evidence with JSON reporting. (github_poc): https://github.com/mehmet-emir-eroglu/CVE-2026-76466

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76466 and fix it if it is affected.

What it is: CVE-2026-76466 is a critical vulnerability in Cisco TelePresence Video Communication Server (VCS) Expressway, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-76466 in the wild and no public exploit code.

Affected product: Cisco TelePresence Video Communication Server (VCS) Expressway. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-76466/ (Markdown: https://insights.sbomify.com/CVE-2026-76466/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76466
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76466
- OSV: https://osv.dev/vulnerability/CVE-2026-76466

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-76466/
Summaries are generated and may contain mistakes; the official description above is the record.