CVE-2026-77321 TREK MCP trip summary bypasses delegated OAuth read scopes
An attacker with a limited OAuth token can access unauthorized trip details and member emails due to missing scope checks in the MCP tool.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-77321?
CVE-2026-77321 is a medium-severity missing authorization vulnerability in mauriceboe TREK, published on 24 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
TREK is a collaborative travel planner. Prior to 3.3.0, the get_trip_summary tool in server/src/mcp/tools/trips.ts is registered for scoped OAuth MCP tokens without requiring trips:read and returns core trip summary data regardless of the delegated scopes. A token granted only an unrelated capability, such as weather:read, can receive trip metadata, member email addresses from server/src/services/tripService.ts, itinerary days, and accommodations for every trip accessible to the token's user. Cross-user trip authorization remains enforced, but the missing scope check defeats the consented least-privilege boundary and exposes trip content and third-party contact information to an MCP client that was not authorized to read it. This issue is fixed in version 3.3.0.
Which versions are affected by CVE-2026-77321?
How do I fix CVE-2026-77321?
No fix has been published for CVE-2026-77321 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-2026-77321 being exploited?
There is no known exploitation of CVE-2026-77321 in the wild and no public exploit code.
Sources
Also known as GHSA-qvw8-w937-vcmq.