CVE-2021-36775 — rancher
HIGHCVE-2021-36775 is a high-severity (CVSS 8.8) CWE-284 vulnerability in github.com/rancher/rancher. A fix is available for github.com/rancher/rancher — see the affected versions and patch details below.
Rancher's Failure to delete orphaned role bindings does not revoke project level access from group based authentication
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-2021-36775 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 378,567 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/rancher/rancher🐹github.com/rancher/rancher🐹github.com/rancher/rancherReal-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
This vulnerability only affects customers using group based authentication in Rancher versions up to and including 2.4.17, 2.5.11 and 2.6.2.
When removing a Project Role associated to a group from a project, the bindings that grant access to cluster scoped resources for those subjects do not get deleted. This happens due to an incomplete authorization logic check. A user who is a member of an affected group with authenticated access to Rancher could use this to access resources they should no longer have access to. The exposure level will depend on the original permission level granted to the affected project role.
Patches
Patched versions include releases 2.4.18, 2.5.12, 2.6.3 and later versions.
Workarounds
Limit access in Rancher to trusted users. There is not a direct mitigation besides upgrading to the patched Rancher versions.
References
Cluster and project roles documentation for Rancher 2.6, 2.5 and 2.4.
For more information
If you have any questions or comments about this advisory:
- Reach out to SUSE Rancher Security team for security related inquiries.
- Open an issue in Rancher repository.
- Verify our support matrix and product support lifecycle.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/rancher/rancher | all versions | 2.4.18go get github.com/rancher/rancher@v2.4.18 |
| 🐹Go | github.com/rancher/rancher | ≥ 2.5.0&&< 2.5.12 | 2.5.12go get github.com/rancher/rancher@v2.5.12 |
| 🐹Go | github.com/rancher/rancher | ≥ 2.6.0&&< 2.6.3 | 2.6.3go get github.com/rancher/rancher@v2.6.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/rancher/rancher, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/rancher/rancher to 2.4.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-36775 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-2021-36775 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-36775. 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-2021-36775 in your dependencies?
O3 Security finds CVE-2021-36775 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.