Metalama: Local code execution via DLL planting in world-writable temporary directories (Linux/macOS)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-62847
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-30 21:17:13 UTC
Updated2026-10-30 23:17:12 UTC
DescriptionMetalama 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.

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Problem Types: CWE-377 | CWE-427 | CWE-377 CWE-377: Insecure Temporary File | CWE-427 CWE-427: Uncontrolled Search Path Element

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.2HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
3.1CNADECLARED8.2HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Metalama Metalama affected < 2025.1.18 Not specified
CNA Metalama Metalama affected >= 2025.2.0-preview, <= 2025.2.5-rc Not specified
CNA Metalama Metalama affected >= 2026.0.0-preview, < 2026.0.25 Not specified
CNA Metalama Metalama affected >= 2026.1.0-preview, < 2026.1.19 Not specified

References

ReferenceSourceLinkTags
github.com/metalama/Metalama/releases/tag/release/2026.0.25 [email protected] github.com
github.com/metalama/Metalama/commit/92c4feecfce86d18fcb007ab6d3a1b438332... [email protected] github.com
github.com/metalama/Metalama/pull/1650 [email protected] github.com
github.com/metalama/Metalama/commit/09911349a916e82194b1cfaa6d0a38acad92... [email protected] github.com
github.com/metalama/Metalama/security/advisories/GHSA-m6wq-39m7-9xpp [email protected] github.com
github.com/metalama/Metalama/releases/tag/release/2026.1.19 [email protected] github.com
github.com/metalama/Metalama/releases/tag/release/2025.1.18 [email protected] github.com
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