# CVE-2026-42563: dulwich: Dulwich is a pure-Python implementation of the Git file formats and protocols

CVE-2026-42563 is fixed in dulwich on 1 platform by DEBIAN-CVE-2026-42563 (version 1.2.5-1), released June 29, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-42563
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0056
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 10, 2026

## Description

Dulwich is a pure-Python implementation of the Git file formats and protocols. Starting in version 0.24.0 and prior to version 1.2.5, Dulwich's `ProcessMergeDriver` substitutes the file path (from the git tree, controllable by an attacker via a malicious branch) into the merge driver command via the `%P` placeholder and executes it with `subprocess.run(..., shell=True)`. An attacker who can cause a victim to merge an untrusted branch can achieve arbitrary command execution by crafting malicious file paths. Version 1.2.5 fixes the issue.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | dulwich Debian 14 | 1.2.5-1 | [DEBIAN-CVE-2026-42563](https://patchblox.com/security/data/fix/linux/debian-cve-2026-42563.md) | Jun 29, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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