OS Command Injection in dulwich (CVE-2026-42563)
Summary
OS command injection in dulwich (CVE-2026-42563). Risk of unauthorized operations or information disclosure. Exploitable via ProcessMergeDriver. Mitigation: upgrade to 1.2.5 or later.
Original description
The description as published by the source.
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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-42563 has been found in dulwich.
Attackers can target a specific entry point like ProcessMergeDriver over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade dulwich to 1.2.5 or later.
If unsure, ask your IT team or search "dulwich CVE-2026-42563" on the vendor's site.
CVE-2026-42563 (dulwich) — CWE-78
Attack surface: ProcessMergeDriver / merge.py / merge_drivers.py / cmd
Patched: 1.2.5 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
OS command injection (CWE-78) exists in dulwich. Attackers reach the vulnerable code path via ProcessMergeDriver.
Check the vendor advisory for the affected versions of dulwich. Attack surface: ProcessMergeDriver / merge.py / merge_drivers.py / cmd.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 1.2.5.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'dulwich' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'dulwich' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
dulwichを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade dulwich to 1.2.5ステージング環境で 1.2.5 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-42563 dulwich
- Ubuntu UBUNTU-CVE-2026-42563 dulwich
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- web github.com
- web github.com