How severe is CVE-2026-45539?

CVE-2026-45539 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-45539 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-45539?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-45539 have an EU (EUVD) identifier?

Yes. CVE-2026-45539 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30561.

When was CVE-2026-45539 published?

CVE-2026-45539 was published on 2026-05-15 and last updated on 2026-06-17.

CVE-2026-45539

CVE-2026-45539 is a high-severity vulnerability with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-59.

Key facts

Severity: High (CVSS 3.x base score 7.4)
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30561
Weakness: CWE-59
Published: 2026-05-15
Last modified: 2026-06-17

Description

Microsoft APM is an open-source, community-driven dependency manager for AI agents. From 0.5.4 to 0.12.4, 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 vulnerability is fixed in 0.13.0.

Frequently asked questions

What is CVE-2026-45539?: Microsoft APM is an open-source, community-driven dependency manager for AI agents. From 0.5.4 to 0.12.4, 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 vulnerability is fixed in 0.13.0.
How severe is CVE-2026-45539?: CVE-2026-45539 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-45539 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-45539?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-45539 have an EU (EUVD) identifier?: Yes. CVE-2026-45539 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30561.
When was CVE-2026-45539 published?: CVE-2026-45539 was published on 2026-05-15 and last updated on 2026-06-17.

References

https://github.com/microsoft/apm/security/advisories/GHSA-q5pp-gvjg-h7v4

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