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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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
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.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-79537 being exploited?
There is no known exploitation of CVE-2026-79537 in the wild and no public exploit code.
Sources
Also known as GHSA-5xqq-w6xh-vwc6.