# CVE-2026-79537: Missing authorization in n/a

> Attackers can hijack sessions to execute private tools and exfiltrate data from other tenants due to missing session ownership validation.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 Sep 2026
- **Updated:** 30 Sep 2026
- **Also known as:** GHSA-5xqq-w6xh-vwc6

## What is CVE-2026-79537?

CVE-2026-79537 is a critical missing authorization vulnerability in n/a, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

metatool-ai MetaMCP through 2.4.22 contains an insecure direct object reference (IDOR) in the MCP transport session dispatch. The session store (getSession in session-lifetime-manager.ts) is keyed only by the client-supplied mcp-session-id header with no owner, namespace, or endpoint binding, and the per-endpoint authorization middleware validates only the URL endpoint's owner, never the session. An attacker who supplies another tenant's session id " obtained without authentication from GET /metamcp/health/sessions, which discloses active session IDs and namespace UUIDs " can list and execute the victim tenant's private MCP tools and exfiltrate their data using the victim's forwarded credentials.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-79537?


## How do I fix CVE-2026-79537?

No fix has been published for CVE-2026-79537 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-79537 being exploited?

There is no known exploitation of CVE-2026-79537 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-79537 and fix it if it is affected.

What it is: CVE-2026-79537 is a critical missing authorization vulnerability in n/a, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-79537 in the wild and no public exploit code.

Affected product: n/a. 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-2026-79537/ (Markdown: https://insights.sbomify.com/CVE-2026-79537/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-79537
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-79537
- OSV: https://osv.dev/vulnerability/CVE-2026-79537

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-79537/
Summaries are generated and may contain mistakes; the official description above is the record.