CVE-2026-47712
LowCVSS 3.3Exploitation Probability (EPSS)
Low risk4th percentile - higher than 4% of all known CVEs
Summary
A vulnerability in Dulwich (versions 0.24.0 through 1.2.4) allows writing patch files outside the intended directory via a malicious commit subject. The format_patch function derives filenames from commit subjects without sanitizing path separators or parent-directory components.
Risk Assessment
An attacker can write a patch file to an arbitrary filesystem location, potentially overwriting critical files or escalating privileges in environments processing untrusted commits with Dulwich.
Recommendation
Upgrade Dulwich to version 1.2.5 or later immediately. If upgrading is not possible, validate the output path or use stdout instead of file output.
Other vulnerabilities in Dulwich
See all- CVE-2026-114095Medium
Dulwich before 1.2.9 contains a denial of service vulnerability in Pack.resolve_object that allows attackers to cause infinite recursion via self-referential OFS_DELTA objects. Attackers can supply a malicious packfile with an OFS_DELTA delta_offset of 0 to exhaust CPU during clone, fetch, or cat-file operations.
- CVE-2015-0838High
Buffer overflow in the C implementation of the apply_delta function in _pack.c in Dulwich before version 0.9.9 allows remote attackers to execute arbitrary code via a crafted pack file.
- CVE-2014-9706High
The build_index_from_tree function in index.py in Dulwich before version 0.9.9 allows remote attackers to execute arbitrary code via a commit with a directory path starting with .git/, which is not properly handled when checking out a working tree.
- CVE-2017-16228Critical
Dulwich before version 0.18.5, when using an SSH subprocess, allows remote attackers to execute arbitrary commands via an ssh URL with an initial dash character in the hostname.
- CVE-2026-114098High
Dulwich from 0.22.5 before 1.2.8 contains a path traversal vulnerability in stash.py pop() that allows attackers to write arbitrary files outside the worktree through intermediate directory symlinks. Attackers can craft a malicious repository whose popped stash writes a payload into .git/hooks/post-checkout, achieving code execution on the next checkout.
- CVE-2026-114097High
Dulwich from 0.23.1 before 1.2.8 contains a path traversal vulnerability in CommitFilter._apply_index_filter() that allows attackers to write files outside the working directory via symlinks persisting between commits. Attackers can craft a repository where an ancestor commit's symlink redirects a descendant commit's file writes during filter_branch, enabling code execution by writing into .git/hooks.
- CVE-2026-114096High
Dulwich from 0.24.0 before 1.2.8 contains a symlink following vulnerability in porcelain.checkout(paths=[...]) that allows attackers to write arbitrary files by abusing raw os.open without O_NOFOLLOW. Attackers can craft a repository where a worktree symlink points to .git/hooks/post-checkout, so restoring the file from a tag writes a malicious hook for code execution.
- CVE-2026-114094High
Dulwich before 1.2.9 fails to validate DOS drive letter prefixes in Git tree path elements on Windows, allowing arbitrary file write. Attackers can craft a malicious repository with a tree entry named 'C:' that bypasses NTFS validation and writes files outside the worktree to achieve remote code execution.
- CVE-2026-38974Medium
Dulwich through version 1.1.0 is missing SSH host key verification in contrib/paramiko_vendor.py. This means that during SSH connections, the server's public key is not checked for trustworthiness.
- CVE-2026-52726High
Dulwich versions 0.23.2 through 1.2.5 do not validate submodule paths during recursive clone. An attacker can craft a malicious .gitmodules and gitlink tree with path .git/hooks, causing files to be written into the victim's .git/hooks directory. Executable files are then run on any hook invocation, leading to remote code execution.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS