CVE-2026-97209

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CVE-2026-97209

Summary: Insecure temporary file in mix deps.partition lets a local user execute code in another user's dependency build

Details: 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, https://osv.dev/vulnerability/EEF-CVE-2026-97209, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97209.json, https://github.com/elixir-lang/elixir/security/advisories/GHSA-96q6-xhwp-fc8q, https://nvd.nist.gov/vuln/detail/CVE-2026-97209, 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