Metalama allows local code execution through DLL planting in shared temporary directories

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.0 · CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:P/VC:L/VI:H/VA:L/SC:L/SI:H/SA:H · score source

EPSS

• CVE-2026-62847: 0.15% estimated exploitation activity in the next 30 days; percentile 4.30 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Metalama loaded and executed compile-time assemblies, auxiliary executable tools, and embedded helper assemblies from predictable temporary directories. On Linux and macOS the default cache location was the world-writable system temporary directory (Path.GetTempPath(), i.e. /tmp), and previously-generated artifacts were trusted based on the presence of a sentinel/.completed marker file rather than on any integrity verification. A local, unprivileged user on a shared machine or CI/build agent can pre-create the deterministic cache directory structure and plant a malicious DLL together with the matching sentinel file. When a higher-privileged user (or build/service account) subsequently runs a build, Metalama finds the sentinel, skips regeneration, and loads and executes the attacker-supplied assembly inside the compiler / IDE / MSBuild process. Affected load-and-execute paths: - the cache of compile-time assemblies that Metalama generates from your aspects; - auxiliary…

Published by the source

14 Oct 2026, 19:24 UTC

Last modified by the source

14 Oct 2026, 19:30 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-m6wq-39m7-9xpp

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-m6wq-39m7-9xpp

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# Patch Next advisory brief: CVE-2026-62847

Advisory: Metalama allows local code execution through DLL planting in shared temporary directories
IDs: CVE-2026-62847, GHSA-m6wq-39m7-9xpp
Record: https://patchnext.com/advisories/cve-2026-62847 (revision 3, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: metalama.tool 2026.1.19, 2026.0.25, 2025.1.18; metalama.framework 2026.1.19, 2026.0.25, 2025.1.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet metalama.tool: affected >= 2026.1.0-preview, < 2026.1.19; < 2025.1.18; >= 2026.0.0-preview, < 2026.0.25; fixed in 2026.0.25, 2026.1.19, 2025.1.18
- NuGet metalama.framework: affected >= 2026.1.0-preview, < 2026.1.19; < 2025.1.18; >= 2026.0.0-preview, < 2026.0.25; fixed in 2026.0.25, 2026.1.19, 2025.1.18

## Suggested inspection (read-only)
- NuGet metalama.tool: check the installed version with your package manager.
- NuGet metalama.framework: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on metalama.tool, metalama.framework.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-m6wq-39m7-9xpp (OSV record GHSA-m6wq-39m7-9xpp lists affected ranges: NuGet metalama.framework >=2026.1.0-preview =0 =2026.0.0-preview =2026.1.0-preview =0 =2026.0.0-preview <2026.0.25 (fixed))
- Verified: https://github.com/advisories/GHSA-m6wq-39m7-9xpp (GitHub-reviewed advisory GHSA-m6wq-39m7-9xpp lists affected ranges: NuGet metalama.framework >=2026.1.0-preview =0 =2026.0.0-preview =2026.1.0-preview =0 =2026.0.0-preview <2026.0.25)

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