CVE-2026-42563
Dulwich Vulnerable to Command Injection via Merge Driver Path
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.
How to fix CVE-2026-42563
To remediate CVE-2026-42563, upgrade the affected package to a fixed version below.
- Debian/dulwich—no fix listed
- —upgrade to 1.2.5 or later
Is CVE-2026-42563 being exploited?
No exploitation signal available. Neither CISA KEV nor a current EPSS score has been published for CVE-2026-42563.
Affected packages (2)
- from 0
- >= 0.24.0, < 1.2.5
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |