CVE-2026-33758CWE-116CWE-20CWE-79

OpenBao has Reflected XSS in its OIDC authentication error message

Critical · published March 27, 2026

CVSS v4.0
9.4
EPSS
0%
Percentile
38.0
In the wild
Unconfirmed
What it is

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`.

The record
Technical detail
CVSS v4.0
9.4 · CRITICAL
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
EPSS
0.00449 · 38.0th percentile
Weaknesses
CWE-116 · Improper Encoding or Escaping of Output; CWE-20 · Improper Input Validation; CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-03-27T14:12Z
EPSS history
Timeline
  • 27 MAR 14:12Z
    OpenBao has Reflected XSS in its OIDC authentication error message
    cvelistv5