CVE-2026-33343 — v3
NONECVE-2026-33343 is a none-severity (CVSS 0) CWE-863 vulnerability in go.etcd.io/etcd/v3. A fix is available for go.etcd.io/etcd/v3 — see the affected versions and patch details below.
etcd: Nested etcd transactions bypass RBAC authorization checks
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-2026-33343.
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.
How urgent is this, really
CVE-2026-33343 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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
Impact
What kind of vulnerability is it? Who is impacted?
An authenticated user with RBAC restricted permissions on key ranges can use nested transactions to bypass all key-level authorization. This allows any authenticated user with direct access to etcd to effectively ignore all key range restrictions, accessing the entire etcd data store.
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.
Patches
Has the problem been patched? What versions should users upgrade to?
This vulnerability is patched in the following versions:
- etcd 3.6.9
- etcd 3.5.28
- etcd 3.4.42
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
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
- require strong client identity at the transport layer, such as mTLS with tightly scoped client certificate distribution
Reporters
Our community helps keep etcd secure
SIG-Etcd thanks community members Luke Francis and Battulga Byambaa for reporting this vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | go.etcd.io/etcd/v3 | ≥ 3.6.0-alpha.0&&< 3.6.9 | 3.6.9go get go.etcd.io/etcd/v3@v3.6.9 |
| 🐹Go | go.etcd.io/etcd/v3 | ≥ 3.5.0-alpha.0&&< 3.5.28 | 3.5.28go get go.etcd.io/etcd/v3@v3.5.28 |
| 🐹Go | go.etcd.io/etcd/v3 | all versions | 3.4.42go get go.etcd.io/etcd/v3@v3.4.42 |
| 🐹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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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-2026-33343 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33343 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33343. 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-2026-33343 in your dependencies?
O3 Security finds CVE-2026-33343 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.