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  5. CVE-2026-45539

CVE-2026-45539: Microsoft APM: Symlinks under `.apm/prompts/` and `.apm/agents/` are dereferenced during `apm install`, copying host-local file contents into the project tree

May 18, 2026

Two primitive integrators in apm-cli enumerate package files with bare Path.glob() / Path.rglob() calls and read each match with Path.read_text(), transparently following symbolic links.

A symlink committed inside a remote APM dependency under .apm/prompts/<x>.prompt.md or .apm/agents/<x>.agent.md is preserved verbatim into apm_modules/ on clone and then dereferenced during integration, with the resolved content written as a regular file into the project’s deploy directories.

The package content_hash, the pre-deploy SecurityGate scan, and apm audit do not flag this. The deploy roots are not added to the auto-generated .gitignore, so the resulting files are staged by git add by default.

This was reproduced via the standard owner/repo#tag install flow against a real bare git repository. No --force or special flags were used.

References

  • github.com/advisories/GHSA-q5pp-gvjg-h7v4
  • github.com/microsoft/apm/commit/f85b9f54ad303159f9c448268eb7005c319fe02a
  • github.com/microsoft/apm/releases/tag/v0.13.0
  • github.com/microsoft/apm/security/advisories/GHSA-q5pp-gvjg-h7v4
  • nvd.nist.gov/vuln/detail/CVE-2026-45539

Code Behaviors & Features

Detect and mitigate CVE-2026-45539 with GitLab Dependency Scanning

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Affected versions

All versions starting from 0.5.4 before 0.13.0

Fixed versions

  • 0.13.0

Solution

Upgrade to version 0.13.0 or above.

Impact 7.4 HIGH

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

Learn more about CVSS

Weakness

  • CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-59: Improper Link Resolution Before File Access ('Link Following')

Source file

pypi/apm/CVE-2026-45539.yml

Spotted a mistake? Edit the file on GitLab.

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