# CVE-2026-47712: Dulwich doesn't sanitize commit subjects in `porcelain.format_patch` > Attackers can write patch files outside the intended directory via malicious commit subjects in Dulwich's format_patch function. - **Severity:** Low 3.3 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 10 Jun 2026 - **Updated:** 11 Jun 2026 - **Also known as:** CLEANSTART-2026-UA20126, CLSA-2026-1784164011, DEBIAN-CVE-2026-47712, ECHO-5850-4d68-024e, GHSA-555p-6grf-mh7f, MINI-x6q7-pwp4-w446, PYSEC-2026-2462, UBUNTU-CVE-2026-47712 ## What is CVE-2026-47712? CVE-2026-47712 is a low-severity path traversal vulnerability in jelmer dulwich, published on 10 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. ### Official description 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. Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) ## Which versions are affected by CVE-2026-47712? 3 open source packages ship an affected version, including dulwich. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `dulwich` | PyPI | From 0.24.0 | 1.2.5 | | `dulwich` | PyPI | From 0.24.0 | 1.2.5 | | `dulwich` | PyPI | From 0.24.0 | 1.2.5 | ## How do I fix CVE-2026-47712? Upgrade dulwich to 1.2.5 or later. ## Is CVE-2026-47712 being exploited? There is no known exploitation of CVE-2026-47712 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-47712 and fix it if it is affected. What it is: CVE-2026-47712 is a low-severity path traversal vulnerability in jelmer dulwich, published on 10 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2026-47712 in the wild and no public exploit code. Affected packages and fixed versions: - dulwich (PyPI): affected from 0.24.0; fixed in 1.2.5 - dulwich (PyPI): affected from 0.24.0; fixed in 1.2.5 - dulwich (PyPI): affected from 0.24.0; fixed in 1.2.5 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-47712/ (Markdown: https://insights.sbomify.com/CVE-2026-47712/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-47712 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-47712 - OSV: https://osv.dev/vulnerability/CVE-2026-47712 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-47712/ Summaries are generated and may contain mistakes; the official description above is the record.