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Vulnerability · Published Mar 27, 2026 · Assigned by GitHub_M

CVE-2026-33758OpenBao has Reflected XSS in its OIDC authentication error message

Critical 9.6

In plain English

A critical-severity improper input validation in openbao from openbao. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.6Critical
Exploit odds (30 days)0.3%top 77.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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 `callback_mode=direct` configured are vulnerable to XSS via the `error_description` 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 `error_description` parameter has been replaced with a static error message in v2.5.2. The vulnerability can be mitigated by removing any roles with `callback_mode` set to `direct`.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.23openbao2.5.4-r0ALPINE-CVE-2026-33758
Alpine:v3.24openbao2.5.4-r0ALPINE-CVE-2026-33758
Gogithub.com/openbao/openbao0.0.0-20260325133417-6e2b2dd84f0eGHSA-cpj3-3r2f-xj59
Gogithub.com/openbao/openbao0.0.0-20260325133417-6e2b2dd84f0eGO-2026-4862

Affected products (as reported)

VendorProductVersions
openbao openbao < 2.5.2

Weakness: CWE-20, CWE-79, CWE-116 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

References