Turbo: Unexpected local code execution during Yarn Berry detection

### Impact Turborepo can be vulnerable to arbitrary code execution when run in untrusted repositories that contain malicious Yarn configuration. In affected versions, package manager detection executed `yarn --version` from the project directory, which could cause Yarn to load and execute a project-controlled `yarnPath` from `.yarnrc.yml`. An attacker who controls repository contents could cause code execution when a user or CI system runs affected `turbo`, `@turbo/codemod`, or `@turbo/workspace` conversion commands. ### Fix Turbo now avoids executing project-local Yarn during package manager detection. Yarn versions and paths are inferred from metadata such as `package.json`, parsing the value of `yarnPath` in `.yarnrc.yml` rather than executing it, and `yarn.lock`, and unrecognized Yarn lockfile formats are rejected instead of falling back to executing `yarn`. ### Workarounds If you cannot upgrade immediately, do not run Turborepo commands in untrusted repositories. Review or remove `.yarnrc.yml` files that define `yarnPath` before running Turborepo, especially in CI or automated tooling that processes external projects.

Source published

19 May 2026 19:46:44 UTC

Source modified

10 Sep 2026 03:51:04 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N

Publisher rating · LOW