{"id":"DEBIAN-CVE-2026-47712","details":"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.porcelain.format_patch(outdir=...) derives each patch filename from the commit's subject line. Prior to this fix, get_summary only replaced spaces with dashes - path separators (/, \\), parent-directory components (..), and other filename-hostile characters (e.g. :) were preserved verbatim and passed straight into os.path.join(outdir, f\"{i:04d}-{summary}.patch\"). A malicious commit subject could therefore direct the generated patch file outside the requested outdir. This is fixed in Dulwich 1.2.5. Users should upgrade to 1.2.5 or later. dulwich.patch.get_summary now mirrors git's format_sanitized_subject: only `[A-Za-z0-9._]` are kept, runs of other characters collapse to a single -, consecutive . collapse to a single ., trailing ./- are stripped, and the result is length-limited. This makes the returned string safe to embed as a filename component, so format_patch can no longer be steered out of outdir via the commit subject. Until upgrading, callers that pass untrusted commits to   porcelain.format_patch can use stdout=True and write the patch to a destination they control, rather than letting format_patch choose the filename; validate the chosen path before opening - e.g. compare os.path.realpath(returned_path) against  os.path.realpath(outdir) and reject any patch whose resolved path is not inside outdir; and/or pre-screen commits and refuse to format any whose subject's first line contains /, \\, .., or other characters that are not safe on the target filesystem.","modified":"2026-09-01T16:06:47.443189450Z","published":"2026-06-10T23:16:48.650Z","upstream":["CVE-2026-47712"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-47712"}],"affected":[{"package":{"name":"dulwich","ecosystem":"Debian:12","purl":"pkg:deb/debian/dulwich?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.21.2-1","0.21.5-1","0.21.6-1","0.22.5-1","0.22.7-1","0.22.7-2","0.24.10-1","0.24.2-1","0.24.2-2","1.0.0-1","1.0.0-2","1.1.0-1","1.1.0-2","1.1.0-3","1.2.0-1","1.2.1-1","1.2.11-1","1.2.12-1","1.2.5-1","1.2.7-1","1.2.7-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47712.json"}},{"package":{"name":"dulwich","ecosystem":"Debian:13","purl":"pkg:deb/debian/dulwich?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.22.7-1","0.22.7-2","0.24.10-1","0.24.2-1","0.24.2-2","1.0.0-1","1.0.0-2","1.1.0-1","1.1.0-2","1.1.0-3","1.2.0-1","1.2.1-1","1.2.11-1","1.2.12-1","1.2.5-1","1.2.7-1","1.2.7-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47712.json"}},{"package":{"name":"dulwich","ecosystem":"Debian:14","purl":"pkg:deb/debian/dulwich?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.5-1"}]}],"versions":["0.22.7-1","0.22.7-2","0.24.10-1","0.24.2-1","0.24.2-2","1.0.0-1","1.0.0-2","1.1.0-1","1.1.0-2","1.1.0-3","1.2.0-1","1.2.1-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-47712.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N"}]}