How severe is CVE-2026-33758?

No CVSS score has been assigned to CVE-2026-33758 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-33758?

CVE-2026-33758 affects the following packages: github.com/openbao/openbao (Go). Ecosystems affected: Go.

How do I fix CVE-2026-33758?

Update github.com/openbao/openbao to 0.0.0-20260325133417-6e2b2dd84f0e or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33758 is resolved across your whole dependency graph.

How do I detect CVE-2026-33758 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openbao/openbao, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-33758 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-33758 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33758 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-33758?

CVE-2026-33758 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 23th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-33758?

CVE-2026-33758 is classified as Improper Input Validation (CWE-20), Cross-site Scripting (XSS) (CWE-79), CWE-116 (CWE-116). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-33758 published, and has it been updated?

CVE-2026-33758 was published on March 27, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-33758 — openbao

Fix: openbao/openbao@6e2b2dd

CVE-2026-33758 is a Improper Input Validation vulnerability in github.com/openbao/openbao. A fix is available for github.com/openbao/openbao — see the affected versions and patch details below.

OpenBao has Reflected XSS in its OIDC authentication error message

Also known asBIT-openbao-2026-33758GHSA-cpj3-3r2f-xj59GO-2026-4862

Published

Mar 27, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33758.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs23th percentile — riskier than 23% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐹github.com/openbao/openbao

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/openbao/openbao`	all versions	0.0.0-20260325133417-6e2b2dd84f0e`go get github.com/openbao/openbao@v0.0.0-20260325133417-6e2b2dd84f0e`

Affected Products

1 product · 1 configurations

Application

openbaoopenbao

< 2.5.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openbao/openbao, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/openbao/openbao to 0.0.0-20260325133417-6e2b2dd84f0e or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33758 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

To exploit this vulnerability, an attacker needs to convince a user to visit a crafted URL, limiting the exposure of this flaw. Due to this reason, this issue has been rated with an important severity.

Workaround published by Red Hat

To mitigate this vulnerability, review JWT/OIDC authentication configurations and remove or disable any roles that have 'callback_mode=direct'.

Source: Red Hat security advisory for CVE-2026-33758 (CC BY 4.0)

Frequently Asked Questions

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

O3 Security · Impact-Aware SCA

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