CVE-2026-33343
etcd: Nested etcd transactions bypass RBAC authorization checks
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, 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. 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 require strong client identity at the transport layer, such as mTLS with tightly scoped client certificate distribution.
How to fix CVE-2026-33343
To remediate CVE-2026-33343, upgrade the affected package to a fixed version below.
- —upgrade to 3.4.42 or later
- —no fix listed
- —no fix listed
- —no fix listed
- —upgrade to 3.6.9 or later
- —upgrade to 3.4.42 or later
Is CVE-2026-33343 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (6)
- from 0, < 3.4.42, >= 3.5.0, < 3.5.28, >= 3.6.0, < 3.6.9
- from 0
- from 0, <= 3.3.27
- from 0
- >= 3.6.0-alpha.0, < 3.6.9
- from 0, < 3.4.42, >= 3.5.0-alpha.0, < 3.5.28, >= 3.6.0-alpha.0, < 3.6.9
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | NONE0.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N |