CVE-2026-97209
Description
Insecure Temporary File vulnerability in Mix deps.partition in Elixir allows a local user to execute code as another user via a swapped partition config file. Partitioned dependency compilation passes the project configuration to each partition VM through a file in a fixed-name directory under the shared system temporary directory, and the partition trusts what it reads back. Another local user on the same host can exploit this during a mix deps.compile run that uses partitioned compilation. Mix.Tasks.Deps.Partition.server/4 in lib/mix/lib/mix/tasks/deps.partition.ex creates the directory with File.mkdir_p/1, which accepts an existing directory without checking its owner, so a user who created it first can replace the file before client/0 reads it. This issue affects mix: from 1.20.0-rc.4 before 1.20.5.
References
- https://cna.erlef.org/cves/CVE-2026-97209.html
- https://github.com/elixir-lang/elixir/commit/55eb91220a1de14dc5aa27029d1f45b0f5832b2d
- https://github.com/elixir-lang/elixir/commit/7f3d95b60c28ae3026a5c1bf943166391245bfd1
- https://github.com/elixir-lang/elixir/commit/9adbe955c8664f4be77d879dd38c003dd39fa777
- https://github.com/elixir-lang/elixir/security/advisories/GHSA-96q6-xhwp-fc8q