GHSA-7q7g-x6vg-xpc3 BIT-openbao-2026-33757 CVE-2026-33757 GO-2026-4860

OpenBao lacks user confirmation for OIDC direct callback mode

High Go

Severity: 9.6 / 10; High · CVSS 3.1
Exploit chance (EPSS): 0.42%; Chance of exploitation in the next 30 days. Higher than 36.16% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-384 Session Fixation
Fix: 0.0.0-20260325142553-e32103951925; Upgrade github.com/openbao/openbao to this version or later

Description

Impact

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.

Patches

Version 2.5.2 includes an additional confirmation screen for direct type logins that requires manual user interaction in order to finish the authentication.

Workarounds

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 versions

Go

Package	Vulnerable	Fixed in
github.com/openbao/openbao	`< 0.0.0-20260325142553-e32103951925`	`0.0.0-20260325142553-e32103951925`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

github.com/openbao/openbao Go → `0.0.0-20260325142553-e32103951925`

go

go get github.com/openbao/openbao@v0.0.0-20260325142553-e32103951925 && go mod tidy

Severity breakdown

CVSS 3.1 9.6

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Changed
Confidentiality: High
Integrity: High
Availability: Low

Weakness

CWE-384: Session Fixation

Authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions.

How to prevent it

Architecture and Design: Invalidate any existing session identifiers prior to authorizing a new user session.
Architecture and Design: For platforms such as ASP that do not generate new values for sessionid cookies, utilize a secondary cookie. In this approach, set a secondary cookie on the user's browser to a random value and set a session variable to the same value. If the session variable and the cookie value ever don't match, invalidate the session, and force the user to log on again.
Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2026-33757

Packages

github.com/openbao/openbao

Timeline

Mar 26, 2026 Published
Jul 27, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-xp3c-3jw3-4vcr OpenBao Skips Stricter Deny Policy for LIST operations	Medium	Also affects github.com/openbao/openbao
GHSA-34fc-gh42-pj53 OpenBao's Recovery Mode Vulnerable To Token Leakage via Timing Attack	Critical	Also affects github.com/openbao/openbao
GHSA-444v-8vxr-p36h OpenBao Agent Writes Secrets to Stdout	Low	Also affects github.com/openbao/openbao
GHSA-59w7-v8rr-pr4p OpenBao's Templated Policies Allow Privilege Escalation via Wildcard Characters	High	Also affects github.com/openbao/openbao
GHSA-8w8f-r2xv-4q4j OpenBao: Transit secrets engine crashes on key creation with `derived: true` for asymmetric key types	Medium	Also affects github.com/openbao/openbao
GHSA-mwr2-wmgp-crj6 OpenBao's System Backend allows Unauthorized Management of the containing Namespace	Low	Also affects github.com/openbao/openbao
GHSA-c36x-h252-g9x2 OpenBao: Cross-namespace lease revocation/renewal via canonical sys/leases/{revoke,renew} — incomplete fix of CVE-2026-45808	Low	Also affects github.com/openbao/openbao
GHSA-6mwx-4547-5vc9 OpenBao: LDAPi ldaputil (wrong escape func)	Medium	Also affects github.com/openbao/openbao

Is this in your code?

MergeHarbor checks every repository's dependencies against this database, ranks what matters by exploitability and reachability, routes it to the owning team and opens the fix pull request.

Check your repos with MergeHarbor