CVE-2026-33762 — v5
LOWCVE-2026-33762 is a low-severity (CVSS 2.8) CWE-129 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: Missing validation decoding Index v4 files leads to panic
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-2026-33762.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-33762 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
go-git’s index decoder for format version 4 fails to validate the path name prefix length before applying it to the previously decoded path name. A maliciously crafted index file can trigger an out-of-bounds slice operation, resulting in a runtime panic during normal index parsing.
This issue only affects Git index format version 4. Earlier formats (go-git supports only v2 and v3) are not vulnerable to this issue.
An attacker able to supply a crafted .git/index file can cause applications using go-git to panic while reading the index. If the application does not recover from panics, this results in process termination, leading to a denial-of-service (DoS) condition.
Exploitation requires the ability to modify or inject a Git index file within the local repository in disk. This typically implies write access to the .git directory.
Patches
Users should upgrade to v5.17.1, or the latest v6 pseudo-version, in order to mitigate this vulnerability.
Credit
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 | all versions | 5.17.1go get github.com/go-git/go-git/v5@v5.17.1 |
Detection & 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-2026-33762 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33762 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33762. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33762 in your dependencies?
O3 Security finds CVE-2026-33762 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.