Vulnerability · Published Mar 27, 2026 · Assigned by GitHub_M

CVE-2026-33757OpenBao lacks user confirmation for OIDC direct callback mode

Critical 9.6

In plain English

A critical-severity session fixation 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 0.4% (higher than 36% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.6Critical

Exploit odds (30 days)0.4%top 63.7% 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 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Alpine:v3.23	openbao	2.5.4-r0	ALPINE-CVE-2026-33757
Alpine:v3.24	openbao	2.5.4-r0	ALPINE-CVE-2026-33757
Go	github.com/openbao/openbao	0.0.0-20260325142553-e32103951925	GO-2026-4860
Go	github.com/openbao/openbao	0.0.0-20260325142553-e32103951925	GHSA-7q7g-x6vg-xpc3

Affected products (as reported)

Vendor	Product	Versions
openbao	openbao	< 2.5.2

Weakness: CWE-384 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

References

https://github.com/openbao/openbao/security/advisories/GHSA-7q7g-x6vg-xpc3 x_refsource_CONFIRM
https://github.com/openbao/openbao/commit/e32103951925723e9787e33886ab6b6ec20f4964 x_refsource_MISC
https://datatracker.ietf.org/doc/html/rfc8628#section-5.4 x_refsource_MISC
https://access.redhat.com/security/cve/CVE-2026-33757 vdb-entry, x_refsource_REDHAT
RHBZ#2452269 issue-tracking, x_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33757.json x_sadp-csaf-vex