Directory Traversal Affecting python-dulwich-debugsource package, versions <0:0.20.18-1.amzn2023.0.3


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.64% (46th percentile)

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  • Snyk IDSNYK-AMZN2023-PYTHONDULWICHDEBUGSOURCE-18531845
  • published5 Aug 2026
  • disclosed10 Jun 2026

Introduced: 10 Jun 2026

CVE-2026-42305  (opens in a new tab)
CWE-22  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 python-dulwich-debugsource to version 0:0.20.18-1.amzn2023.0.3 or higher.
This issue was patched in ALAS2023-2026-2026.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python-dulwich-debugsource package and not the python-dulwich-debugsource package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

Dulwich is a pure-Python implementation of the Git file formats and protocols. Versions starting with 0.10.0 and prior to 1.2.5 have an 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. 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 Dulwich CLI, porcelain.clone, or any downstream tool built on Dulwich - is impacted. POSIX clones are not directly exploitable (on POSIX \ is a literal filename byte), but a POSIX user can unknowingly propagate a malicious tree to Windows consumers via push or re-publication. This issue is fixed in Dulwich 1.2.5. Users should upgrade to 1.2.5 or later. There is no effective pre-patch workaround. On affected versions the core.protectNTFS configuration key was silently ignored, so setting it to true does not mitigate the issue. Users who cannot upgrade should avoid cloning, fetching, or checking out untrusted repositories with Dulwich on Windows. After upgrading the NTFS validator is on by default on every platform, so no additional configuration is required.

CVSS Base Scores

version 3.1