CVE-2026-46383 Microsoft APM: Windows absolute-path tar member overwrite during legacy-bundle probing in `apm install`
Attackers can overwrite arbitrary files on Windows systems via malicious tar archives during apm install, potentially leading to code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-46383?
CVE-2026-46383 is a medium-severity path traversal vulnerability in microsoft apm, published on 15 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Microsoft APM is an open-source, community-driven dependency manager for AI agents. Prior to 0.13.0, Microsoft APM contains a Windows-specific archive extraction boundary failure in the legacy-bundle probe used by apm install <bundle> on supported Python 3.10 and 3.11 runtimes. When apm install is given a local .tar.gz that is not recognized as a plugin-format bundle, APM probes whether it is a legacy --format apm bundle. On Python versions earlier than 3.12, that probe extracts untrusted tar members with raw tar.extractall() without rejecting Windows absolute member names such as D:/.... This vulnerability is fixed in 0.13.0.
Which versions are affected by CVE-2026-46383?
3 open source packages ship an affected version, including apm-cli.
| Package | Affected | Fixed in |
|---|---|---|
apm-cli PyPI | All versions | 0.13.0 |
apm-cli PyPI | All versions | 0.13.0 |
apm-cli PyPI | All versions | 0.13.0 |
How do I fix CVE-2026-46383?
Upgrade apm-cli to 0.13.0 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-46383 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46383 exists.
Sources
Also known as GHSA-mq5j-pw29-jcv3, PYSEC-2026-2378.