Insecure temporary file in mix deps.partition lets a local user execute code in another user's dependency build
Summary
| CVE | CVE-2026-97209 |
|---|---|
| State | PUBLISHED |
| Assigner | EEF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-30 09:17:15 UTC |
| Updated | 2026-10-30 09:17:15 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 5.4 MEDIUM from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-377 | CWE-377 CWE-377 Insecure Temporary File
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | Secondary | 5.4 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 5.4 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Elixir-lang | Elixir | affected 1.20.0-rc.4 1.20.5 semver | Not specified |
| CNA | Elixir-lang | Elixir | affected 7f3d95b60c28ae3026a5c1bf943166391245bfd1 * git | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/elixir-lang/elixir/commit/7f3d95b60c28ae3026a5c1bf94316639124... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/elixir-lang/elixir/commit/9adbe955c8664f4be77d879dd38c003dd39... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| osv.dev/vulnerability/EEF-CVE-2026-97209 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | osv.dev | |
| cna.erlef.org/cves/CVE-2026-97209.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | cna.erlef.org | |
| github.com/elixir-lang/elixir/security/advisories/GHSA-96q6-xhwp-fc8q | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/elixir-lang/elixir/commit/55eb91220a1de14dc5aa27029d1f45b0f58... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Quinn Wilton (en)
CNA: Quinn Wilton (en)
CNA: José Valim (en)
CNA: Jonatan Männchen / EEF (en)
Additional Advisory Data
Workarounds
CNA: On a multi-user host, set TMPDIR to a private per-user directory with mode 0700 before running Mix, so that System.tmp_dir/0 resolves to a location other users cannot pre-create or read. Alternatively, keep partitioned compilation disabled by leaving MIX_OS_DEPS_COMPILE_PARTITION_COUNT unset or at 1, which keeps the configuration inside the parent process.