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CVE-2026-42305 high CVSS 8.8

Path Traversal in dulwich (CVE-2026-42305)

Summary

Path traversal in dulwich (CVE-2026-42305). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 1.2.5 or later.

Original description

The description as published by the source.

Impact

Arbitrary file write leading to remote code execution when cloning or checking out a malicious Git repository on Windows.

Dulwich's path-element validator accepted tree entries whose filenames contained bytes that Windows interprets as structural path syntax:

  • \ — the Windows path separator. A single tree entry named .git\hooks\pre-commit.exe was treated as one valid filename on POSIX but materialized as nested directories .git/hooks/pre-commit.exe on Windows, planting a file inside the victim's .git directory. Git for Windows then
    executes that hook on the next git commit, giving the attacker arbitrary code execution in the victim's user context. The same primitive can be used with ..\outside.txt to escape the work tree.
  • : — the NTFS alternate-data-stream marker. .git::$INDEX_ALLOCATION writes directly into the victim's .git entity, bypassing the .git-as-a-directory check.
  • git~ — NTFS 8.3 short-name aliases of .git. Only the literal git1 was rejected; git2, git10, GIT1, etc. were all accepted.

Contributing configuration bugs made matters worse. The core.protectNTFS and core.protectHFS settings were looked up under a wrong option name and so user-set values were silently ignored, and core.protectNTFS only defaulted to true on Windows (Git upstream has defaulted it to true everywhere since CVE-2019-1353). Both have been corrected.

Anyone who clones, fetches, or checks out an untrusted repository with Dulwich on Windows - either through the Dulwi…

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-2026-42305 has been found in dulwich.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade dulwich to 1.2.5 or later.
If unsure, ask your IT team or search "dulwich CVE-2026-42305" on the vendor's site.

CVE-2026-42305 (dulwich) — CWE-22 / CVSS v3 8.8
Attack vector: remote (network-reachable) / unauthenticated
Patched: 1.2.5 — apply immediately
Workaround: There is no effective pre-patch workaround.
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.

❓ What is the problem

Path traversal (CWE-22) exists in dulwich.

📍 Affected scope

Check the vendor advisory for the affected versions of dulwich.

🔥 Severity

Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 1.2.5.

🛡️ Workaround

Workaround: There is no effective pre-patch workaround.

🔍 Detection

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

  1. 1
    Identify 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。

  2. 2
    Apply temporary workaround mitigate 
    There is no effective pre-patch workaround.

    パッチが適用されるまでの応急処置として、There is no effective pre-patch workaround. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply 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。

  4. 4
    Post-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

pip dulwich
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.5"}]}]
PyPI dulwich
[{"type":"ECOSYSTEM","events":[{"introduced":"0.10.0"},{"fixed":"1.2.5"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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