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Fencer Vulns
medium 6.1

CVE-2026-53766 json

chrome-devtools-mcp: validatePath() does not canonicalize symlinks before enforcing roots

published 2026-06-24 4 mo ago modified 2026-10-25 14 d ago also GHSA-8qf9-62x2-82pp , EUVD-2026-39104

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

Chrome DevTools for agents (chrome-devtools-mcp) lets your coding agent control and inspect a live Chrome browser. From 0.24.0 until 1.1.0, McpContext.validatePath() enforces workspace roots by checking whether path.resolve(filePath) textually falls under one of the configured root paths. path.resolve() does not canonicalize symbolic links. As a result, a symlink inside a configured workspace root can point to a file outside that root, pass validation, and then be followed by downstream file read/write operations. This bypass applies even when the MCP client correctly declares the roots capability with a non-empty list. It is separate from the documented legacy behavior where missing roots capability allows all paths. The practical impact is a workspace-boundary bypass. In the write direction, filePath-writing tools can overwrite out-of-root files through an in-root symlink. In the read direction, upload_file can read through the symlink and send the file to the currently selected web page. This vulnerability is fixed in 1.1.0.

Patch / fix

  • npm chrome-devtools-mcp 1.1.0
  • google chrome-devtools-mcp 1.1.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/ChromeDevTools/chrome-devtools-mcp/security/advisories/GHSA-8qf9-62x2-82pp referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
GitHub 3.1 6.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

Affected packages

ecosystem package affected fixed in
npm chrome-devtools-mcp
>=0.24.0, <1.1.0
1.1.0

Affected products

  • ChromeDevTools chrome-devtools-mcp

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Vulns 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.