Vulnerability in Openbao

CVE-2026-33757

OpenBao is an open source identity-based secrets management system. Prior to version 2.5.2, OpenBao does not prompt for user confirmation when logging in via JWT/OIDC and a role with `callback_mode` set to `direct`. This allows an attacker to start an authentication request and perform "remote phishing" by having the victim visit the URL and automatically log-in to the session of the attacker. Despite being based on the authorization code flow, the `direct` mode calls back directly to the API and allows an attacker to poll for an OpenBao token until it is issued. Version 2.5.2 includes an additional confirmation screen for `direct` type logins that requires manual user interaction in order to finish the authentication. This issue can be worked around either by removing any roles with `callback_mode=direct` or enforcing confirmation for every session on the token issuer side for the Client ID used by OpenBao.

EPSS: 0.004 (33.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-33757?
CVE-2026-33757 is a critical-severity vulnerability in Openbao, classified under Session Fixation. CVSS score: 9.6/10. Published 2026-03-27.
How severe is CVE-2026-33757?
Critical severity. CVSS v3 base score is 9.6 out of 10.