Dulwich doesn't sanitize commit subjects in `porcelain.format_patch`

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Summary

CVECVE-2026-47712
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-10 23:16:48 UTC
Updated2026-06-11 15:21:07 UTC
DescriptionDulwich 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.

Risk And Classification

Primary CVSS: v3.1 3.3 LOW from [email protected]

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Problem Types: CWE-22 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.3LOWCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
3.1CNADECLARED3.3LOWCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jelmer Dulwich affected >= 0.24.0, < 1.2.5 Not specified

References

ReferenceSourceLinkTags
github.com/jelmer/dulwich/security/advisories/GHSA-555p-6grf-mh7f [email protected] github.com
github.com/jelmer/dulwich/commit/c2446e51b [email protected] github.com
github.com/jelmer/dulwich/releases/tag/dulwich-1.2.5 [email protected] github.com
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