# CVE-2026-100408: Git for Windows credential helper heap overflow in wincred

Source: https://junglewise.ai/threats/cve-2026-100408-git-for-windows-is-the-windows-port-of-git-from-2-43-0-windows-1  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-04. Updated: 2026-11-04  
License: CC BY 4.0 with a link back

CVE-2026-100408 · Severity: medium · CVSS 4.4 · Published 2026-11-04

Git for Windows includes a credential helper that stores authentication tokens securely. When erasing stored credentials, a memory corruption flaw causes the helper to crash or fail silently, leaving rejected credentials stored in Windows Credential Manager. An attacker with local access could exploit this to prevent credential removal, potentially maintaining unauthorized access to git repositories.

Vendors: [Git](https://junglewise.ai/threats/vendors/git).

## Quick answers

**Is CVE-2026-100408 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100408 being exploited in the wild.

**How severe is CVE-2026-100408?** Medium severity, with a CVSS score of 4.4, published 4 November 2026.

**Which products and versions are affected?** Git for Windows 2.43.0.windows.1 to 2.55.0.windows.2.

**Is there a fix for CVE-2026-100408?** Yes: fixed in Git for Windows 2.55.0.windows.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-100408 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-100408?** Check whether you run Git for Windows at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Git for Windows 2.55.0.windows.3

## Technical details

A buffer overflow exists in contrib/credential/wincred/git-credential-wincred.c's match_cred_password() function when processing a git credential reject command with a password field. The code allocates a buffer sized in bytes but instructs wcsncpy_s() to copy wide characters, causing a two-byte NUL write past the allocation boundary. This triggers heap corruption and process termination (status 0xC0000374) before the credential deletion completes, masking the failure to the caller.

## Affected products

- Git Git for Windows 2.43.0.windows.1 to 2.55.0.windows.2

## Timeline

- 2026-11-04: disclosed

## References

- [https://github.com/git-for-windows/git/commit/b4d1fb62c7e2fdcab5a018e25e51acb196eb1756](https://github.com/git-for-windows/git/commit/b4d1fb62c7e2fdcab5a018e25e51acb196eb1756)
- [https://github.com/git-for-windows/git/releases/tag/v2.55.0.windows.3](https://github.com/git-for-windows/git/releases/tag/v2.55.0.windows.3)