CVE-2026-89039: CVE Record
The convertplaywrightscript prompt in the k6 MCP server accepts a file path as its playwrightscript argument. Paths given in the documented '@'-prefixed form are restricted to the server's current working directory, but a bare path is resolved by a separate undocumented code path that applies no such restriction. A caller able to invoke the prompt can therefore read any file readable by the user running the server, including files outside the working directory, and receives the file contents in the prompt response. A leading '~' is expanded to the user's home directory, so credential files such as SSH private keys are directly addressable. The working-directory restriction is additionally bypassable through a symbolic link inside the working directory that points outside it, because the path is not canonicalized before the restriction is applied. All releases from v0.3.0 onward are affected; releases v0.3.0 and v0.4.0 apply no restriction to either form.
Affected Software
Event History
Frequently Asked Questions
Which versions require remediation?
All releases from v0.3.0 onward are affected. In v0.3.0 and v0.4.0, neither the documented '@'-prefixed path form nor bare paths have a working-directory restriction.
What access does an attacker need to read files?
The attacker must be able to invoke the convert_playwright_script prompt in the k6 MCP server. They can read files that are readable by the operating-system user running the server.
Can the documented '@'-prefixed path syntax be relied on to confine reads to the working directory?
No. Although that form applies a working-directory restriction in later affected releases, a symbolic link inside the working directory that points outside it bypasses the restriction because paths are not canonicalized first.