{"cve":"CVE-2026-42305","nvd":{"published":"2026-06-10T23:16:46.113","modified":"2026-07-23T09:10:00.113","status":"Deferred","description":"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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-22"],"references":["https://github.com/jelmer/dulwich/commit/49eb56e51aad637fc23d54bf2a08cb42739b8290","https://github.com/jelmer/dulwich/commit/57efc4aa1581e038915a0fd79365be53b150f4a9","https://github.com/jelmer/dulwich/releases/tag/dulwich-1.2.5","https://github.com/jelmer/dulwich/security/advisories/GHSA-897w-fcg9-f6xj"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:38:48.522727527+00:00"},"epss":{"cve":"CVE-2026-42305","score":0.00635,"percentile":0.50464,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-897w-fcg9-f6xj","url":"https://osv.dev/vulnerability/GHSA-897w-fcg9-f6xj","summary":"Dulwich has an arbitrary file write via NTFS-hostile tree entries on Windows","modified":"2026-09-10T03:51:04.871562898Z","packages":[{"ecosystem":"PyPI","name":"dulwich","purl":"pkg:pypi/dulwich","ranges":[">=0.10.0 <1.2.5"],"fixed":["1.2.5"]}]},{"id":"PYSEC-2026-2463","url":"https://osv.dev/vulnerability/PYSEC-2026-2463","summary":"Dulwich has an arbitrary file write via NTFS-hostile tree entries on Windows","modified":"2026-07-13T16:31:45.611264999Z","packages":[{"ecosystem":"PyPI","name":"dulwich","purl":"pkg:pypi/dulwich","ranges":[">=0.10.0 <1.2.5"],"fixed":["1.2.5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}