Bug 2451727 (CVE-2026-33343)

Summary: CVE-2026-33343 etcd: etcd: Authorization bypass allows information disclosure via nested transactions
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: eglynn, jjoyce, jschluet, lhh, mburns, mgarciac
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in etcd, a distributed key-value store. An authenticated user with Role-Based Access Control (RBAC) restricted permissions on key ranges can exploit this flaw by using nested transactions. This bypasses all key-level authorization, allowing the user to access the entire etcd data store. This can lead to significant information disclosure.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2452160, 2452161    
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Description OSIDB Bzimport 2026-03-26 14:03:21 UTC 
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.