etcd-io etcd up to 3.4.41/3.5.27/3.6.8 authorization

Summaryinfo

A vulnerability categorized as critical has been discovered in etcd-io etcd up to 3.4.41/3.5.27/3.6.8. This vulnerability affects unknown code. Executing a manipulation can lead to authorization. This vulnerability is registered as CVE-2026-33343. It is possible to launch the attack remotely. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in etcd-io etcd up to 3.4.41/3.5.27/3.6.8. This vulnerability affects an unknown functionality. The manipulation with an unknown input leads to a authorization vulnerability. The CWE definition for the vulnerability is CWE-863. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-33343 since 03/18/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 304371 (Azure Linux 3.0 Security Update: CBL-Mariner Releases (CVE-2026-33343)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 3.4.42, 3.5.28 or 3.6.9 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (304371) and CERT Bund (WID-SEC-2026-0818). Once again VulDB remains the best source for vulnerability data.

Affected

• Open Source etcd

Productinfo

Vendor

• etcd-io

Name

• etcd

Version

• 3.4.0
• 3.4.1
• 3.4.2
• 3.4.3
• 3.4.4
• 3.4.5
• 3.4.6
• 3.4.7
• 3.4.8
• 3.4.9
• 3.4.10
• 3.4.11
• 3.4.12
• 3.4.13
• 3.4.14
• 3.4.15
• 3.4.16
• 3.4.17
• 3.4.18
• 3.4.19
• 3.4.20
• 3.4.21
• 3.4.22
• 3.4.23
• 3.4.24
• 3.4.25
• 3.4.26
• 3.4.27
• 3.4.28
• 3.4.29
• 3.4.30
• 3.4.31
• 3.4.32
• 3.4.33
• 3.4.34
• 3.4.35
• 3.4.36
• 3.4.37
• 3.4.38
• 3.4.39
• 3.4.40
• 3.4.41
• 3.5.0
• 3.5.1
• 3.5.2
• 3.5.3
• 3.5.4
• 3.5.5
• 3.5.6
• 3.5.7
• 3.5.8
• 3.5.9
• 3.5.10
• 3.5.11
• 3.5.12
• 3.5.13
• 3.5.14
• 3.5.15
• 3.5.16
• 3.5.17
• 3.5.18
• 3.5.19
• 3.5.20
• 3.5.21
• 3.5.22
• 3.5.23
• 3.5.24
• 3.5.25
• 3.5.26
• 3.5.27
• 3.6.0
• 3.6.1
• 3.6.2
• 3.6.3
• 3.6.4
• 3.6.5
• 3.6.6
• 3.6.7
• 3.6.8

Website

• Product: https://github.com/etcd-io/etcd/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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