🛡️ CVE-2026-33758 — openbao

🔴 CVSS 9.5 — Critical ✅ No Known Exploit CWE-20 OSV
9.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

OpenBao has Reflected XSS in its OIDC authentication error message

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2026-33758 is classified as CWE-20: Improper Input Validation. The application accepts input without checking that it has the expected form, so malformed values reach code that assumes they are well formed.

Affected software

CVE-2026-33758 is recorded against 2 packages.

  • github.com/openbao/openbao
  • openbao

Timeline and source

Published on 26 March 2026 and last revised on 27 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)

Details

Severity CRITICAL
CVSS Score 9.5
CVSS 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
CWE CWE-20
Public Exploit ✅ No
Source OSV
Published 2026-03-26
Updated 2026-08-12
Modified 2026-07-27

Affected Packages

Software From version Fixed in
github.com/openbao/openbao — —
openbao — —

Similar Threats

Exploit Protection

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