CVE-2026-100408: Memory Corruption (CVSS 4.4)

Description

Git for Windows is the Windows port of Git. From 2.43.0.windows.1 until 2.55.0.windows.3, when a matching git:* credential exists in Windows Credential Manager and a git-credential-wincred erase input includes a password field, the operation in contrib/credential/wincred/git-credential-wincred.c allocates a buffer of exactly CredentialBlobSize bytes in match_cred_password() and then uses wcsncpy_s() to copy the corresponding number of wide characters plus a terminating NUL. The destination capacity is also supplied in bytes instead of WCHAR elements, allowing a fixed two-byte NUL write past the allocation before the password comparison determines whether CredDeleteW() should remove the credential; erase without a password field does not enter this comparison path. The helper can terminate with Windows heap-corruption status, and git credential reject can appear successful while the rejected credential remains stored. This issue is fixed in version 2.55.0.windows.3.

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CVSS v3.1 Score

4.4

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L

EPSS — Exploit Prediction

0.0012

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-787 Out-of-bounds Write

References

Other References

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/security/advisories/GHSA-5j7x-r6vf-jhq2 https://github.com/git-for-windows/git/security/advisories/GHSA-5j7x-r6vf-jhq2

Frequently Asked Questions

What is CVE-2026-100408? +

Git for Windows is the Windows port of Git. From 2.43.0.windows.1 until 2.55.0.windows.3, when a matching git:* credential exists in Windows Credential Manager and a git-credential-wincred erase input includes a password field, the operation in contrib/credential/wincred/git-credential-wincred.c allocates a buffer of exactly CredentialBlobSize bytes in match_cred_password() and then uses wcsncpy_s() to copy the corresponding number of wide characters plus a terminating NUL. The destination capacity is also supplied in bytes instead of WCHAR elements, allowing a fixed two-byte NUL write past the allocation before the password comparison determines whether CredDeleteW() should remove the credential; erase without a password field does not enter this comparison path. The helper can terminate with Windows heap-corruption status, and git credential reject can appear successful while the rejected credential remains stored. This issue is fixed in version 2.55.0.windows.3. It has a CVSS v3.1 base score of 4.4 (MEDIUM).

How severe is CVE-2026-100408? +

CVE-2026-100408 has a CVSS v3.1 score of 4.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0012, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-100408? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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