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Fencer Intel
medium 4.3

CVE-2026-77321 json

TREK MCP trip summary bypasses delegated OAuth read scopes

published 4mo ago modified last mo. also EUVD-2026-86339 , GHSA-qvw8-w937-vcmq

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository liketrek/TREK. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

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.

Patch / fix

  • mauriceboe trek 3.3.0

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Affected products

  • mauriceboe TREK

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-284 Improper Access Control
  • CWE-862 Missing Authorization

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of liketrek/TREK published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.