CVE-2026-62847
Metalama: Local code execution via DLL planting in world-writable temporary directories (Linux/macOS)
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High8.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H |
| NVDNVD · Deferred | 3.1 | High8.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.15% · top 96% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.2.
Weakness
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- NuGetMetalama.FrameworkGHSA-m6wq-39m7-9xpp (opens in a new tab)
- NuGetMetalama.ToolGHSA-m6wq-39m7-9xpp (opens in a new tab)
References (7)
- https://github.com/metalama/Metalama/security/advisories/GHSA-m6wq-39m7-9xpp (opens in a new tab)x_refsource_CONFIRM
- https://github.com/metalama/Metalama/pull/1650 (opens in a new tab)x_refsource_MISC
- https://github.com/metalama/Metalama/commit/09911349a916e82194b1cfaa6d0a38acad928fc9 (opens in a new tab)x_refsource_MISC
- https://github.com/metalama/Metalama/commit/92c4feecfce86d18fcb007ab6d3a1b4383326a2e (opens in a new tab)x_refsource_MISC
- https://github.com/metalama/Metalama/releases/tag/release/2025.1.18 (opens in a new tab)x_refsource_MISC
- https://github.com/metalama/Metalama/releases/tag/release/2026.0.25 (opens in a new tab)x_refsource_MISC
- https://github.com/metalama/Metalama/releases/tag/release/2026.1.19 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-m6wq-39m7-9xpp (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-62847)Record last updated .