CVE-2021-3499
MEDIUMCVE-2021-3499 is a medium-severity (CVSS 5.6) CWE-863 vulnerability in github.com/ovn-org/ovn-kubernetes. O3 Security confirms whether CVE-2021-3499 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Improper Input Validation
Real-World Exposure
github.com/ovn-org/ovn-kubernetesReal-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
A vulnerability was found in OVN Kubernetes in versions up to and including 0.3.0 where the Egress Firewall does not reliably apply firewall rules when there is multiple DNS rules. It could lead to potentially lose of confidentiality, integrity or availability of a service.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/ovn-org/ovn-kubernetes | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ovn-org/ovn-kubernetes. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of github.com/ovn-org/ovn-kubernetes has shipped for CVE-2021-3499 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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 pinpoints whether CVE-2021-3499 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-3499. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
In OpenShift Container Platform 4 the default Container Network Interface (CNI) network provider plug-in is OpenShift SDN, and it's not affected by this flaw. Only the OVN-Kubernetes CNI network provider is affected.
Frequently Asked Questions
Is CVE-2021-3499 in your dependencies?
O3 detects CVE-2021-3499 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.