CVE-2026-62847
Dashboard / Vulnerabilities / CVE-2026-62847
Summary: Metalama: Local code execution via DLL planting in world-writable temporary directories (Linux/macOS)
Details: Metalama is a Roslyn-based open-source patterns and architecture toolkit for C#. Prior to 2025.1.18, 2026.0.25 and 2026.1.19, Metalama.Framework and Metalama.Tool load and execute compile-time assemblies, auxiliary executable tools and embedded helper assemblies from predictable temporary directories. On `Linux` and `macOS`, the default `Path.GetTempPath()` location is world-writable, and existing artifacts are trusted based on sentinel or `.completed` marker files rather than integrity verification. A local unprivileged user on a shared machine or CI/build agent can pre-create the deterministic directory structure and plant a malicious DLL with the matching sentinel. When a higher-privileged developer or build account subsequently builds, Metalama skips regeneration and executes the planted artifact in the compiler, IDE or MSBuild process as the building user. This permits cross-user privilege escalation, reading source and secrets, supply-chain tampering with build output, or disrupting builds. Default Windows per-user temporary directories are protected by ACLs and are not affected. Deployer-selected insecure cache locations are outside the vulnerability's scope. This issue is fixed in versions 2025.1.18, 2026.0.25 and 2026.1.19.
References: https://github.com/metalama/Metalama/releases/tag/release/2025.1.18, https://github.com/metalama/Metalama/releases/tag/release/2026.0.25, https://github.com/metalama/Metalama/releases/tag/release/2026.1.19, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/62xxx/CVE-2026-62847.json, https://github.com/metalama/Metalama/security/advisories/GHSA-m6wq-39m7-9xpp, https://nvd.nist.gov/vuln/detail/CVE-2026-62847, https://github.com/metalama/Metalama/commit/09911349a916e82194b1cfaa6d0a38acad928fc9, https://github.com/metalama/Metalama/commit/92c4feecfce86d18fcb007ab6d3a1b4383326a2e, https://github.com/metalama/Metalama/pull/1650
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