# OpenBao has Reflected XSS in its OIDC authentication error message

Advisory record · `GHSA-cpj3-3r2f-xj59`

- **Identifiers:** `GHSA-cpj3-3r2f-xj59` · `BIT-openbao-2026-33758` · `CVE-2026-33758` · `GO-2026-4862`
- **State:** Confirmed
- **Severity:** CVSS 9.4 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-20](https://cwe.mitre.org/data/definitions/20.html) · [CWE-79](https://cwe.mitre.org/data/definitions/79.html) · [CWE-80](https://cwe.mitre.org/data/definitions/80.html) · [CWE-116](https://cwe.mitre.org/data/definitions/116.html)
- **Tags:** [Cross-site scripting (XSS)](https://agentprime.io/advisories/tag/xss.md) · [CWE-20](https://agentprime.io/advisories/tag/cwe-20.md) · [CWE-116](https://agentprime.io/advisories/tag/cwe-116.md)
- **Published:** 26 Mar 2026
- **Updated:** 27 Jul 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 26 Mar 2026, 18:37 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.4: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `github.com/openbao/openbao` (Go): affected `<0.0.0-20260325133417-6e2b2dd84f0e`; fixed in `0.0.0-20260325133417-6e2b2dd84f0e`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 9.4 Critical, CVSS 4.0: `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`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0030, the 22nd percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:56 UTC: First seen by agentprime
- 31 Oct 2026, 14:56 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-cpj3-3r2f-xj59)

## Sources

- [GitHub Advisory Database: GHSA-cpj3-3r2f-xj59](https://github.com/advisories/GHSA-cpj3-3r2f-xj59)
- [OSV: GHSA-cpj3-3r2f-xj59](https://osv.dev/vulnerability/GHSA-cpj3-3r2f-xj59)
- <https://github.com/openbao/openbao/security/advisories/GHSA-cpj3-3r2f-xj59>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-33758>
- <https://github.com/openbao/openbao/pull/2709>
- <https://github.com/openbao/openbao/commit/6e2b2dd84f0e47cebc90d6e79609dd5274732662>
- <https://github.com/openbao/openbao>
- <https://github.com/openbao/openbao/releases/tag/v2.5.2>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-cpj3-3r2f-xj59>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-cpj3-3r2f-xj59/>. Everything for agents: <https://agentprime.io/llms.txt>.