# CVE-2026-33757: OpenBao session fixation via OIDC direct callback mode

Source: https://junglewise.ai/threats/cve-2026-33757-openbao-session-fixation-via-oidc-direct-callback-mode  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-27. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-33757 · Severity: critical · CVSS 9.6 · Published 2026-03-27

OpenBao is an open-source tool used by organizations to manage and protect sensitive information like passwords and encryption keys. A security flaw in its login process allows an attacker to trick a user into unintentionally authorizing a login session for the attacker. If successful, the attacker could gain full access to the victim's secrets and credentials, potentially leading to a total compromise of sensitive corporate data.

Technologies: [github.com/openbao/openbao (Go)](https://junglewise.ai/threats/technologies/github-com-openbao-openbao), [OpenBao](https://junglewise.ai/threats/technologies/openbao). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [OpenBao](https://junglewise.ai/threats/vendors/openbao).

## Quick answers

**Is CVE-2026-33757 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-33757 being exploited in the wild.

**How severe is CVE-2026-33757?** Critical severity, with a CVSS score of 9.6, published 27 March 2026.

**Which products and versions are affected?** github.com/openbao/openbao (Go) SEMVER:introduced=0,fixed=0.0.0-20260325142553-e32103951925; OpenBao < 2.5.2.

**Is there a fix for CVE-2026-33757?** Yes. github.com/openbao/openbao (Go): upgrade to 0.0.0-20260325142553-e32103951925 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-33757 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-33757?** Check whether you run github.com/openbao/openbao (Go) or OpenBao at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/openbao/openbao (Go): upgrade to 0.0.0-20260325142553-e32103951925 or later

  ```sh
  go get github.com/openbao/openbao@v0.0.0-20260325142553-e32103951925
  ```


## Technical details

A session fixation vulnerability exists in OpenBao's JWT/OIDC authentication backend when a role is configured with `callback_mode` set to `direct`. The implementation lacks a manual confirmation step, allowing an attacker to initiate an authentication request and lure a victim to the verification URL. Because the `direct` mode communicates back to the API without user intervention, the attacker can poll the API until a token is issued to their own session upon the victim's successful authentication. This is a violation of the security considerations in RFC 8628 (OAuth 2.0 Device Authorization Grant). The vulnerability is resolved in version 2.5.2 by introducing a mandatory confirmation screen.

## Affected products

- OpenBao OpenBao < 2.5.2

## Identifiers

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

## Timeline

- 2026-03-25: patched: Fix committed to repository
- 2026-03-27: disclosed: Initial advisory published

## References

- [https://datatracker.ietf.org/doc/html/rfc8628](https://datatracker.ietf.org/doc/html/rfc8628)
- [https://github.com/openbao/openbao/commit/e32103951925723e9787e33886ab6b6ec20f4964](https://github.com/openbao/openbao/commit/e32103951925723e9787e33886ab6b6ec20f4964)
- [https://github.com/openbao/openbao/security/advisories/GHSA-7q7g-x6vg-xpc3](https://github.com/openbao/openbao/security/advisories/GHSA-7q7g-x6vg-xpc3)
- [https://access.redhat.com/security/cve/CVE-2026-33757](https://access.redhat.com/security/cve/CVE-2026-33757)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2452269](https://bugzilla.redhat.com/show_bug.cgi?id=2452269)
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33757.json](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33757.json)

## Related threats

- [OpenBao policy cache incorrect authorization via namespace traversal](https://junglewise.ai/threats/cve-2026-115365-openbao-from-2-3-0-before-2-6-3-contains-an-incorrect)
- [OpenBao ACL bypass in policy denial evaluation](https://junglewise.ai/threats/cve-2026-115361-openbao-before-2-6-3-contains-an-acl-bypass-vulnerability-that)
- [OpenBao Kubernetes Auth token renewal on revoked credentials](https://junglewise.ai/threats/cve-2026-115356-openbao-before-2-6-4-and-2-7-x-before-2-7-1-does-not-verify-when)
- [OpenBao Agent information disclosure via stdout in exec rendering mode](https://junglewise.ai/threats/cve-2026-77285-openbao-agent-information-disclosure-via-stdout-in-exec-rendering)
- [OpenBao recovery mode timing attack token leakage](https://junglewise.ai/threats/cve-2026-63132-openbao-recovery-mode-timing-attack-token-leakage)