CVE-2026-45021
Fix: kumahq/kuma@8fefa85CVE-2026-45021 is a CWE-346 vulnerability in github.com/kumahq/kuma. O3 Security confirms whether CVE-2026-45021 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kuma: Default kuma-cp leaks admin token cross-origin via CORS wildcard + LocalhostIsAdmin
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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-2026-45021.
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.
Real-World Exposure
github.com/kumahq/kuma🐹github.com/kumahq/kuma🐹github.com/kumahq/kuma🐹github.com/kumahq/kuma🐹github.com/kumahq/kumaReal-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
Kuma is a modern Envoy-based service mesh that can run on every cloud across both Kubernetes and VMs. Prior to 2.7.25, 2.9.15, 2.11.13, 2.12.10, and 2.13.5, the default kuma-cp config leaks the admin bootstrap token and signing keys to any webpage the operator visits while the control plane is reachable from their browser. CorsAllowedDomains: [".*"] reflects any Origin, and LocalhostIsAdmin: true promotes requests from 127.0.0.1 to mesh-system:admin. A cross-origin fetch() from a malicious page returns the admin JWT and signing material. This vulnerability is fixed in 2.7.25, 2.9.15, 2.11.13, 2.12.10, and 2.13.5.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/kumahq/kuma | all versions | 2.7.25 |
| 🐹Go | github.com/kumahq/kuma | ≥ 2.9.0&&< 2.9.15 | 2.9.15 |
| 🐹Go | github.com/kumahq/kuma | ≥ 2.11.0&&< 2.11.13 | 2.11.13 |
| 🐹Go | github.com/kumahq/kuma | ≥ 2.12.0&&< 2.12.10 | 2.12.10 |
| 🐹Go | github.com/kumahq/kuma | ≥ 2.13.0&&< 2.13.5 | 2.13.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/kumahq/kuma. 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/kumahq/kuma to 2.7.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45021 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-2026-45021 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-2026-45021. 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-2026-45021 in your dependencies?
O3 detects CVE-2026-45021 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.