Chrome DevTools for agents: daemon.pid write follows symlinks in /tmp fallback runtime directory

Exploitation

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

CVSS

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

EPSS

• CVE-2026-53765: 0.10% estimated exploitation activity in the next 30 days; percentile 0.99 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The chrome-devtools-mcp daemon writes its PID file with fs.writeFileSync() to a deterministic runtime path. On typical macOS environments, and on Linux sessions where $XDGRUNTIMEDIR is unset, that runtime path falls back to /tmp/chrome-devtools-mcp-<uid/daemon.pid. Because the write does not use ONOFOLLOW, a local low-privilege user on the same POSIX host can pre-create /tmp/chrome-devtools-mcp-<victimuid/daemon.pid as a symlink to a file writable by the victim. When the victim later starts daemon mode, fs.writeFileSync() follows the symlink and truncates the target file to the daemon PID string. This report is deliberately scoped to POSIX systems where the daemon falls back to /tmp: typical macOS environments and Linux sessions without $XDGRUNTIMEDIR. Windows is out of scope because the default temp directory is per-user and symlink creation has additional privilege requirements. Details Affected code: src/daemon/daemon.ts:38-42 src/daemon/utils.ts:49-68 The /tmp sticky bit…

Published by the source

17 Jun 2026, 14:01 UTC

Last modified by the source

21 Jul 2026, 13:45 UTC

Source last checked

26 Oct 2026, 12:57 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-3pvj-jv98-qhjq

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-3pvj-jv98-qhjq

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# Patch Next advisory brief: CVE-2026-53765

Advisory: Chrome DevTools for agents: daemon.pid write follows symlinks in /tmp fallback runtime directory
IDs: CVE-2026-53765, GHSA-3pvj-jv98-qhjq
Record: https://patchnext.com/advisories/cve-2026-53765 (revision 2, source checked 26 Oct 2026, 12:57 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: chrome-devtools-mcp 1.1.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm chrome-devtools-mcp: affected >= 0.20.0, <= 1.0.1; fixed in 1.1.0

## Suggested inspection (read-only)
- `npm ls chrome-devtools-mcp --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 chrome-devtools-mcp.
- 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://osv.dev/vulnerability/GHSA-3pvj-jv98-qhjq (OSV record GHSA-3pvj-jv98-qhjq lists affected ranges: npm chrome-devtools-mcp >=0.20.0 <1.1.0 (fixed))
- Verified: https://github.com/advisories/GHSA-3pvj-jv98-qhjq (GitHub-reviewed advisory GHSA-3pvj-jv98-qhjq lists affected ranges: npm chrome-devtools-mcp >=0.20.0 <=1.0.1)

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