Bug 2487758 (CVE-2026-42305)

Summary: CVE-2026-42305 dulwich: Dulwich: Remote Code Execution via Malicious Git Repository
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: anthomas, dschmidt, ehelms, erezende, ggainey, jdobes, jkoehler, jlanda, jpasqual, juwatts, kgaikwad, kshier, lphiri, mdellweg, mhulan, nmoumoul, orabin, osousa, pcreech, rchan, rhel-process-autobot, simaishi, smallamp, smcdonal, stcannon, teagle, tmalecek, watson-tool-maintainers, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Dulwich, a pure-Python implementation of the Git file formats and protocols. A remote attacker could exploit this vulnerability by enticing a user on a Windows system to clone or check out a specially crafted malicious Git repository. This could lead to an arbitrary file write, ultimately resulting in remote code execution on the affected system.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2498479, 2498480    
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Description OSIDB Bzimport 2026-06-10 23:01:42 UTC 
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.