---
title: "CVE-2026-33758: OpenBao has Reflected XSS in its OIDC authentication error message"
url: https://erroneo.us/security/cve/CVE-2026-33758/
description: "CVE-2026-33758 (github.com/openbao/openbao (Go)): OpenBao is an open source identity-based secrets management system. Prior to version 2.5.2, OpenBao…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-27
date_modified: 2026-07-15
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-33758"
kev: false
cvss: 9.4
epss: 0.00449
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-33758: OpenBao has Reflected XSS in its OIDC authentication error message

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.4% , percentile 38: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 38% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Only applies if your dependency tree includes github.com/openbao/openbao (Go) < 0.0.0-20260325133417-6e2b2dd84f0e, fixed in 0.0.0-20260325133417-6e2b2dd84f0e . Check your lockfile, including transitive dependencies.

## What it is

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 callbackmode=direct configured are vulnerable to XSS via the errordescription 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 errordescription parameter has been replaced with a static error message in v2.5.2. The vulnerability can be mitigated by removing any roles with callbackmode set to direct.

## Affected packages

- Go `github.com/openbao/openbao` < 0.0.0-20260325133417-6e2b2dd84f0e → fixed: 0.0.0-20260325133417-6e2b2dd84f0e

## Affected products (CVE record)

- openbao openbao: < 2.5.2

## Severity

- GitHub_M CVSS 4.0: 9.4 `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`
- redhat-SADP CVSS 3.1: 9.6 `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:L`
- GitHub CVSS 4.0: 9.4 `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`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.45% probability of exploitation activity in the next 30 days; percentile 38.

## Sources

- [GitHub Advisory GHSA-cpj3-3r2f-xj59](https://github.com/advisories/GHSA-cpj3-3r2f-xj59)
- [CVE.org record CVE-2026-33758](https://www.cve.org/CVERecord?id=CVE-2026-33758)
- [NVD entry CVE-2026-33758](https://nvd.nist.gov/vuln/detail/CVE-2026-33758)
- [github.com](https://github.com/openbao/openbao/security/advisories/GHSA-cpj3-3r2f-xj59)
- [github.com](https://github.com/openbao/openbao/pull/2709)
- [github.com](https://github.com/openbao/openbao/commit/6e2b2dd84f0e47cebc90d6e79609dd5274732662)
- [github.com](https://github.com/openbao/openbao/releases/tag/v2.5.2)
- [access.redhat.com](https://access.redhat.com/security/cve/CVE-2026-33758)
- [RHBZ#2452294](https://bugzilla.redhat.com/show_bug.cgi?id=2452294)
- [security.access.redhat.com](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33758.json)

---
Source page: https://erroneo.us/security/cve/CVE-2026-33758/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt