CVE-2026-39388 OpenBao's Certificate Authentication Allows Token Renewal With Different Certificate

What is CVE-2026-39388?

CVE-2026-39388 is a low-severity authentication bypass vulnerability in openbao, published on 21 Apr 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

Official description

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.

Weakness: CWE-295

Which versions are affected by CVE-2026-39388?

4 open source packages ship an affected version, including github.com/openbao/openbao and openbao. It affects 1 product.

Products include Openbao Openbao.

How do I fix CVE-2026-39388?

Upgrade github.com/openbao/openbao to 0.0.0-20260420160924-abe84e1af4c3 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-39388 being exploited?

There is no known exploitation of CVE-2026-39388 in the wild and no public exploit code.

Other vulnerabilities in openbao

• CVE-2026-33757 OpenBao lacks user confirmation for OIDC direct callback mode Critical 9.6
• CVE-2026-33758 OpenBao has Reflected XSS in its OIDC authentication error message Critical 9.4
• CVE-2025-54997 OpenBao: Privileged Operator May Execute Code on the Underlying Host Critical 9.1
• CVE-2025-64761 OpenBao Privileged Operator Identity Group Root Escalation High 7.5
• CVE-2025-59043 OpenBao vulnerable to denial of service via malicious JSON request processing High 7.5

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-openbao-2026-39388, GHSA-7ccv-rp6m-rffr, GO-2026-5213.