# CVE-2026-82456: argocd-mcp 0.8.0 Authentication Bypass via Unauthenticated HTTP

> Attackers can bypass authentication to modify Argo CD resources using the operator's token if the server is exposed and configured with an API token.

- **Severity:** Critical 10.0 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Aug 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-p2x5-x87w-v2xj, GHSA-rp45-5x3v-48mr

## What is CVE-2026-82456?

CVE-2026-82456 is a critical authentication bypass vulnerability in argoproj-labs argocd-mcp, published on 29 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

argocd-mcp 0.8.0 binds its HTTP transport to every network interface and accepts MCP sessions without requiring caller credentials when ARGOCD_API_TOKEN is configured. Attackers who can reach the listener can invoke the full tool surface using the operator's stored token to create applications, request syncs, and modify Argo CD resources.

Weakness: CWE-1327 (Binding to an Unrestricted IP Address)

## Which versions are affected by CVE-2026-82456?


## How do I fix CVE-2026-82456?

No fix has been published for CVE-2026-82456 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-82456 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82456 exists.

Public exploit code:

- argocd-mcp 0.8.0 - Unauthenticated MCP Session and Tool Access (nuclei): http/cves/2026/CVE-2026-82456.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82456 and fix it if it is affected.

What it is: CVE-2026-82456 is a critical authentication bypass vulnerability in argoproj-labs argocd-mcp, published on 29 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82456 exists.

Affected product: argoproj-labs argocd-mcp. 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-2026-82456/ (Markdown: https://insights.sbomify.com/CVE-2026-82456/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82456
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82456
- OSV: https://osv.dev/vulnerability/CVE-2026-82456

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82456/
Summaries are generated and may contain mistakes; the official description above is the record.