CVE-2026-33413
etcd: Authorization bypasses in multiple APIs
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.
Blast Radius
go.etcd.io/etcd/v3🐹go.etcd.io/etcd/v3🐹go.etcd.io/etcd/v3🐹go.etcd.io/etcdReal-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
etcd is a distributed key-value store for the data of a distributed system. Prior to versions 3.4.42, 3.5.28, and 3.6.9, unauthorized users may bypass authentication or authorization checks and call certain etcd functions in clusters that expose the gRPC API to untrusted or partially trusted clients. In unpatched etcd clusters with etcd auth enabled, unauthorized users are able to call MemberList and learn cluster topology, including member IDs and advertised endpoints; call Alarm, which can be abused for operational disruption or denial of service; use Lease APIs, interfering with TTL-based keys and lease ownership; and/or trigger compaction, permanently removing historical revisions and disrupting watch, audit, and recovery workflows. Kubernetes does not rely on etcd’s built-in authentication and authorization. Instead, the API server handles authentication and authorization itself, so typical Kubernetes deployments are not affected. Versions 3.4.42, 3.5.28, and 3.6.9 contain a patch. If upgrading is not immediately possible, reduce exposure by treating the affected RPCs as unauthenticated in practice. Restrict network access to etcd server ports so only trusted components can connect and/or require strong client identity at the transport layer, such as mTLS with tightly scoped client certificate distribution.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | go.etcd.io/etcd/v3 | ≥ 3.6.0-alpha.0&&< 3.6.9 | 3.6.9 |
| 🐹Go | go.etcd.io/etcd/v3 | ≥ 3.5.0-alpha.0&&< 3.5.28 | 3.5.28 |
| 🐹Go | go.etcd.io/etcd/v3 | all versions | 3.4.42 |
| 🐹Go | go.etcd.io/etcd | 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 go.etcd.io/etcd/v3. 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 go.etcd.io/etcd/v3 to 3.6.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33413 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-2026-33413 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-2026-33413. 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-2026-33413 in your dependencies?
O3 detects CVE-2026-33413 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.