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-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-2026-38974Medium
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.
- CVE-2026-47734Medium
A vulnerability in Dulwich (versions 0.1.0 through 1.2.4) allows a client with push access to send a crafted thin pack (~174 bytes) whose delta header declares a huge dest_size. When processed by add_thin_pack/apply_delta, it allocates hundreds of MB of memory, potentially causing resource exhaustion.
- CVE-2026-42563High
A vulnerability in the Dulwich library (versions 0.24.0 through 1.2.4) allows arbitrary command execution. An attacker can craft a malicious file path in a Git branch, which is substituted into the merge driver command via the %P placeholder and executed with shell=True when a victim merges the branch.
- CVE-2026-42305High
A vulnerability in the Dulwich library (versions 0.10.0 through 1.2.4) allows remote code execution via arbitrary file write when cloning or checking out a malicious Git repository on Windows. The issue stems from improper validation of path elements that can contain bytes interpreted by Windows as structural path syntax. Additionally, the core.protectNTFS and core.protectHFS security settings were silently ignored due to configuration bugs.
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