CVE-2026-41520
HIGHCVE-2026-41520 is a high-severity (CVSS 7.9) vulnerability in github.com/cilium/cilium. O3 Security confirms whether CVE-2026-41520 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Cillium exposes sensitive information included in the cilium-bugtool debug archive
Blast Radius
github.com/cilium/cilium🐹github.com/cilium/cilium🐹github.com/cilium/ciliumReal-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
Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Prior to versions 1.17.15, 1.18.9, and 1.19.3, the output of cilium-bugtool can contain sensitive data when the tool is run against Cilium deployments with WireGuard encryption enabled. This issue has been patched in versions 1.17.15, 1.18.9, and 1.19.3.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cilium/cilium | all versions | 1.17.15 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.18.0&&< 1.18.9 | 1.18.9 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.19.0&&< 1.19.3 | 1.19.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cilium/cilium. 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 github.com/cilium/cilium to 1.17.15 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41520 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-2026-41520 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-2026-41520. 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-2026-41520 in your dependencies?
O3 detects CVE-2026-41520 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.