# 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.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Sep 2026
- **Updated:** 5 Oct 2026
- **Also known as:** GHSA-qvw8-w937-vcmq

## 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.

Weakness: CWE-862 (Missing Authorization), CWE-284 (Improper Access Control), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## 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.

## Is CVE-2026-77321 being exploited?

There is no known exploitation of CVE-2026-77321 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77321 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-77321 in the wild and no public exploit code.

Affected product: mauriceboe TREK. 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-2026-77321/ (Markdown: https://insights.sbomify.com/CVE-2026-77321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77321
- OSV: https://osv.dev/vulnerability/CVE-2026-77321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77321/
Summaries are generated and may contain mistakes; the official description above is the record.