OpenBao up to 2.5.2 certificate validation

Summaryinfo

A vulnerability was found in OpenBao up to 2.5.2. It has been declared as critical. Affected by this issue is some unknown functionality. The manipulation results in certificate validation. This vulnerability is reported as CVE-2026-39388. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in OpenBao up to 2.5.2. Affected is some unknown processing. The manipulation with an unknown input leads to a certificate validation vulnerability. CWE is classifying the issue as CWE-295. The product does not validate, or incorrectly validates, a certificate. This is going to have an impact on integrity. CVE summarizes:

OpenBao is an open source identity-based secrets management system. Prior to version 2.5.3, OpenBao's Certificate authentication method, when a token renewal is requested and `disable_binding=true` is set, attempts to verify the current request's presented mTLS certificate matches the original. Token renewals for other authentication methods do not require any supplied login information. Due to incorrect matching, the certificate authentication method would allow renewal of tokens for which the attacker had a sibling certificate+key signed by the same CA, but which did not necessarily match the original role or the originally supplied certificate. This implies an attacker could still authenticate to OpenBao in a similar scope, however, token renewal implies that an attacker may be able to extend the lifetime of dynamic leases held by the original token. This attack requires knowledge of either the original token or its accessor. This vulnerability is original from HashiCorp Vault. This is addressed in v2.5.3. As a workaround, ensure privileged roles are tightly scoped to single certificates.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-39388 since 04/07/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1587.003.

The vulnerability scanner Nessus provides a plugin with the ID 311376 (Fedora 44 : openbao (2026-c7450bfed6)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.5.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (311376), EUVD (EUVD-2026-24029) and CERT Bund (WID-SEC-2026-1189). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Open Source OpenBao

Productinfo

Name

• OpenBao

Version

• 2.5.0
• 2.5.1
• 2.5.2

Website

• Product: https://github.com/openbao/openbao/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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