Dulwich Vulnerable to Command Injection via Merge Driver Path
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-78.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| jelmer | dulwich | 0.24.0 to before 1.2.5 | 1.2.5 | Patch available | CNA |
| — | dulwich (PyPI) | 0.24.0 to before 1.2.5 | 1.2.5 | Patch available | GHSA-9277-mp7x-85jf |
- dulwich Vendorjelmer Affected 0.24.0 to before 1.2.5 Fixed in 1.2.5 Patch available CNA
- dulwich (PyPI) Vendor— Affected 0.24.0 to before 1.2.5 Fixed in 1.2.5 Patch available GHSA-9277-mp7x-85jf
Remediation
- Fix · CNA dulwich (jelmer) Fixed in 1.2.5
- Fix · GHSA-9277-mp7x-85jf dulwich (PyPI) Fixed in 1.2.5 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
Not affected: 6 products
- Red Hat Ansible Automation Platform 2
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift AI (RHOAI)
- Red Hat OpenShift Container Platform 4
- Red Hat Satellite 6
Timeline
- 2026-10-02 Threatist record created from CVE-2026-42563
- 2026-10-03 Alias added: GHSA-9277-mp7x-85jf
- 2026-10-25 EPSS moved to the below the 50th percentile
References
More jelmer vulnerabilities
- TI-2026-78707 Path traversal in Dulwich lets attackers write files on Windows CVSS 4.0HIGH 8.7
- TI-2026-37846 Path traversal in jelmer dulwich CVSS 3.1HIGH 7.5
- TI-2026-78709 Symlink following in Dulwich checkout allows arbitrary file writes CVSS 4.0HIGH 7.3
- TI-2026-30613 Dulwich has an arbitrary file write via NTFS-hostile tree entries on Windows CVSS 3.1HIGH 8.8
- TI-2026-85266 Dulwich commit parser picks the wrong tree from duplicate headers CVSS 4.0HIGH 8.6
- TI-2026-78708 Infinite recursion in Dulwich pack parsing causes denial of service CVSS 4.0HIGH 7.1
Sources
- CVE-2026-42563 · CVE Program
- CVE-2026-42563 · NVD
- FIRST EPSS
- GHSA-9277-mp7x-85jf · GitHub Advisory Database · CC BY 4.0
- CVE-2026-42563 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences