CVE-2019-11251
MEDIUMCVE-2019-11251 is a medium-severity (CVSS 5.7) CWE-61 vulnerability in k8s.io/kubernetes. O3 Security confirms whether CVE-2019-11251 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kubernetes kubectl cp Vulnerable to Symlink Attack
Real-World Exposure
k8s.io/kubernetes🐹k8s.io/kubernetes🐹k8s.io/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
The Kubernetes kubectl cp command in versions 1.1-1.12, and versions prior to 1.13.11, 1.14.7, and 1.15.4 allows a combination of two symlinks provided by tar output of a malicious container to place a file outside of the destination directory specified in the kubectl cp invocation. This could be used to allow an attacker to place a nefarious file using a symlink, outside of the destination tree.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | k8s.io/kubernetes | ≥ 1.13.10&&< 1.13.11 | 1.13.11 |
| 🐹Go | k8s.io/kubernetes | ≥ 1.14.6&&< 1.14.7 | 1.14.7 |
| 🐹Go | k8s.io/kubernetes | ≥ 1.15.3&&< 1.16.0 | 1.16.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for k8s.io/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.
Fix
Update k8s.io/kubernetes to 1.13.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-11251 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 pinpoints whether CVE-2019-11251 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-2019-11251. 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.
This issue did not affect the version of Kubernetes(embedded in heketi) shipped with Red Hat Gluster Storage 3 as it does not include the symlink support for kubectl cp.
Frequently Asked Questions
Is CVE-2019-11251 in your dependencies?
O3 detects CVE-2019-11251 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.