mcp-sanitizer: File Path Sanitizer Permits Arbitrary User-Home Absolute Paths

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

File Path Sanitizer Permits Arbitrary User-Home Absolute Paths

Summary `mcp-sanitizer` v1.3.3 explicitly whitelists `/home/` and `/Users/` as allowed absolute path prefixes in its file path validation logic (`src/utils/validation-utils.js:188-196`). As a result, paths such as `/home/alice/.ssh/id_rsa` and `/home/alice/.aws/credentials` pass through `sanitizer.sanitize()` with `blocked=false`, even though they point to highly sensitive files outside any configured safe root. Any consumer application that trusts the sanitized path and passes it to a filesystem read/write operation (e.g., `fs.readFile`) will expose arbitrary user-home directory files to an unauthenticated network attacker. Dynamic reproduction confirmed exfiltration of a simulated SSH private key and AWS credentials via a single HTTP POST request.

Details The vulnerability resides in the `validateFilePath` function inside `src/utils/validation-utils.js`. When an absolute path falls outside the configured safe…

Published by the source

28 Oct 2026, 19:51 UTC

Last modified by the source

28 Oct 2026, 20:00 UTC

Source last checked

29 Oct 2026, 06:00 UTC

1. Revision 2 · amended · 29 Oct 2026

   Amended from osv record GHSA-7w82-6f9j-v9jp

2. Revision 1 · created · 28 Oct 2026

   Published from ghsa record GHSA-7w82-6f9j-v9jp

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# Patch Next advisory brief: GHSA-7w82-6f9j-v9jp

Advisory: mcp-sanitizer: File Path Sanitizer Permits Arbitrary User-Home Absolute Paths
IDs: GHSA-7w82-6f9j-v9jp
Record: https://patchnext.com/advisories/ghsa-7w82-6f9j-v9jp (revision 2, source checked 29 Oct 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mcp-sanitizer 1.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm mcp-sanitizer: affected < 1.4.0; fixed in 1.4.0

## Suggested inspection (read-only)
- `npm ls mcp-sanitizer --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mcp-sanitizer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-7w82-6f9j-v9jp (GitHub-reviewed advisory GHSA-7w82-6f9j-v9jp lists affected ranges: npm mcp-sanitizer >=0 <1.4.0)
- Verified: https://osv.dev/vulnerability/GHSA-7w82-6f9j-v9jp (OSV record GHSA-7w82-6f9j-v9jp lists affected ranges: npm mcp-sanitizer >=0 <1.4.0 (fixed))

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