CVE-2026-33758: OpenBao has Reflected XSS in its OIDC authentication error message
Impact
OpenBao installations that have an OIDC/JWT authentication method enabled and a role with callbackmode=direct configured are vulnerable to XSS via the errordescription parameter on the page for a failed authentication.
This allows an attacker access to the token used in the Web UI by a victim.
Patches The errordescription parameter has been replaced with a static error message in v2.5.2
Workarounds The vulnerability can be mitigated by removing any roles with callbackmode set to direct.
Other sources
OpenBao is an open source identity-based secrets management system. Prior to version 2.5.2, OpenBao installations that have an OIDC/JWT authentication method enabled and a role with callbackmode=direct configured are vulnerable to XSS via the errordescription parameter on the page for a failed authentication. This allows an attacker access to the token used in the Web UI by a victim. The errordescription parameter has been replaced with a static error message in v2.5.2. The vulnerability can be mitigated by removing any roles with callbackmode set to direct.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
go/github.com/openbao/openbaoto a version that resolves this vulnerability.Fixed in 0.0.0-20260325133417-6e2b2dd84f0e - Upgrade
Upgrade
OpenBaoto a version that resolves this vulnerability.Fixed in 2.5.2 - Configuration
Mitigate by removing any roles with `callback_mode=direct` so the failed authentication page no longer exposes an attacker-controlled `error_description` parameter.
OpenBao OIDC/JWT authentication role callback_mode = not direct
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33758?
CVE-2026-33758 has a high severity rating due to its potential for reflected cross-site scripting (XSS) attacks.
How do I fix CVE-2026-33758?
To fix CVE-2026-33758, update OpenBao to the version that is later than 0.0.0-20260325133417-6e2b2dd84f0e.
Who is affected by CVE-2026-33758?
CVE-2026-33758 affects OpenBao installations using OIDC/JWT authentication with `callback_mode=direct`.
What type of vulnerability is CVE-2026-33758?
CVE-2026-33758 is a reflected cross-site scripting (XSS) vulnerability.
What impact does CVE-2026-33758 have?
The impact of CVE-2026-33758 allows attackers to execute arbitrary scripts in the context of the affected user's session.