How severe is CVE-2026-40264?

No CVSS score has been assigned to CVE-2026-40264 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-40264?

CVE-2026-40264 affects the following packages: github.com/openbao/openbao (Go). Ecosystems affected: Go.

How do I fix CVE-2026-40264?

Update github.com/openbao/openbao to 0.0.0-20260420162526-f58111d2ca54 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40264 is resolved across your whole dependency graph.

How do I detect CVE-2026-40264 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-2026-40264 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-40264 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-40264 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-2026-40264?

CVE-2026-40264 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-2026-40264?

CVE-2026-40264 is classified as CWE-1259 (CWE-1259). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-40264 published, and has it been updated?

CVE-2026-40264 was published on April 21, 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-2026-40264 — openbao

Fix: openbao/openbao#2934

CVE-2026-40264 is a CWE-1259 vulnerability in github.com/openbao/openbao. A fix is available for github.com/openbao/openbao — see the affected versions and patch details below.

OpenBao's Token Store Allows Cross-Namespace Renewal, Revocation

Also known asBIT-openbao-2026-40264GHSA-p49j-v9wc-wg57GO-2026-5526

Published

Apr 21, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

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-2026-40264.

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. OpenBao's namespaces provide multi-tenant separation. Prior to version 2.5.3, a tenant who leaks token accessors can have their token revoked or renewed by a privileged administrator in another tenant. This is addressed in v2.5.3.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/openbao/openbao`	all versions	0.0.0-20260420162526-f58111d2ca54`go get github.com/openbao/openbao@v0.0.0-20260420162526-f58111d2ca54`

Affected Products

1 product · 1 configurations

Application

openbaoopenbao

< 2.5.3

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 0.0.0-20260420162526-f58111d2ca54 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40264 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2026-40264 in your dependencies?

Find it across Go, including transitive dependencies.

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