CVE-2026-34165 — go-git
MEDIUMCVE-2026-34165 is a medium-severity (CVSS 5) CWE-191 vulnerability in github.com/go-git/go-git/v5. A fix is available for github.com/go-git/go-git/v5 — see the affected versions and patch details below.
go-git: Maliciously crafted idx file can cause asymmetric memory consumption
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34165.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/go-git/go-git/v5Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
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.
Patches
Users should upgrade to v5.17.1, or the latest v6 pseudo-version, in order to mitigate this vulnerability.
Credit
The go-git maintainers thank @kq5y for finding and reporting this issue privately to the go-git project.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/go-git/go-git/v5 | ≥ 5.0.0&&< 5.17.1 | 5.17.1go get github.com/go-git/go-git/v5@v5.17.1 |
Affected Products
go-gitgo-git_projectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/go-git/go-git/v5, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/go-git/go-git/v5 to 5.17.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34165 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2026-34165 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-34165 in your dependencies?
Find it across Go, including transitive dependencies.