Live › vulnerability › CVE-2026-62847
Metalama.Framework and Metalama.Tool trust compile-time DLLs in predictable temporary directories on Linux and macOS. A local unprivileged user can plant a malicious DLL that runs inside the compiler, IDE or MSBuild as a higher-privileged developer or build account.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-30 21:25 UTC. All times on this page are UTC.
Teams building C# with Metalama on Linux or macOS, especially on shared machines or CI/build agents where a less-privileged local user can write to the default temp directory. Windows per-user temp directories are protected by ACLs and not affected, and insecure cache locations chosen by the deployer are outside the scope of the issue.
No product ranges from the sources yet.
2025.1.18, 2026.0.25 or 2026.1.19, depending on the release line in useEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
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