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Vulnerability · Published Jun 10, 2026 · Assigned by GitHub_M

CVE-2026-42563Dulwich Vulnerable to Command Injection via Merge Driver Path

High 7.7

In plain English

A high-severity OS command injection in dulwich from jelmer. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.7High
Exploit odds (30 days)0.6%top 53.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12dulwichno fix listedDEBIAN-CVE-2026-42563
Debian:13dulwichno fix listedDEBIAN-CVE-2026-42563
Debian:14dulwich1.2.5-1DEBIAN-CVE-2026-42563
PyPIdulwich1.2.5GHSA-9277-mp7x-85jf
PyPIdulwich1.2.5PYSEC-2026-2464
Ubuntu:22.04:LTSdulwichno fix listedUBUNTU-CVE-2026-42563
Ubuntu:24.04:LTSdulwichno fix listedUBUNTU-CVE-2026-42563
Ubuntu:25.10dulwichno fix listedUBUNTU-CVE-2026-42563
Ubuntu:26.04:LTSdulwichno fix listedUBUNTU-CVE-2026-42563
Ubuntu:26.10dulwichno fix listedUBUNTU-CVE-2026-42563

Affected products (as reported)

VendorProductVersions
jelmer dulwich >= 0.24.0, < 1.2.5

Weakness: CWE-78 · Vector: 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

References