Bug 2451728 (CVE-2026-33413)

Summary: CVE-2026-33413 etcd: etcd: Authorization bypass allows information disclosure and denial of service
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: adudiak, alcohan, anjoseph, dschmidt, eglynn, erezende, gparvin, jbalunas, jjoyce, jlanda, jprabhak, jschluet, kshier, lhh, mburns, mgarciac, pahickey, rhaigner, simaishi, smcdonal, stcannon, teagle, wtam, yguenane
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. Unauthorized users can bypass authentication or authorization checks when the gRPC API is exposed to untrusted clients. This allows them to access sensitive cluster topology information, disrupt operations through alarms, interfere with lease management, and trigger data compaction, leading to permanent data loss and disruption of critical workflows. This vulnerability can result in information disclosure and denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2451754, 2451761    
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Description OSIDB Bzimport 2026-03-26 14:03:26 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, 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.