CVE-2026-58251: nats-server Access Control Flaw — Fix

Description

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, an authenticated user with subscription deny permissions could bypass a plain subject deny rule by using a queue subscription, because queue-specific deny evaluation could override the plain subject deny result when the queue name itself was not denied. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.

Is your site exposed to CVE-2026-58251?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS — Exploit Prediction

0.0046

Probability of exploitation

0.37%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-285 CWE-285

Affected Products

Vendor	Product	Versions
linuxfoundation	nats-server	< 2.11.16
linuxfoundation	nats-server	2.12.0 — 2.12.7

References

Advisories & Patches

https://github.com/nats-io/nats-server/commit/013586288078def45a6788096924eb4d150db65c https://github.com/nats-io/nats-server/commit/79c2f6e9ff87f594596337b6427dda85c38d1fe1 https://github.com/nats-io/nats-server/commit/b9ffb63b85e7db3d25a13b2e234f5f7f7c13164d https://github.com/nats-io/nats-server/security/advisories/GHSA-jx8g-9g95-6322

Other References

https://github.com/nats-io/nats-server/releases/tag/v2.11.16 https://github.com/nats-io/nats-server/releases/tag/v2.12.7 https://github.com/nats-io/nats-server/releases/tag/v2.14.0

Frequently Asked Questions

What is CVE-2026-58251? +

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, an authenticated user with subscription deny permissions could bypass a plain subject deny rule by using a queue subscription, because queue-specific deny evaluation could override the plain subject deny result when the queue name itself was not denied. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-58251? +

CVE-2026-58251 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0046, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-58251? +

CVE-2026-58251 affects products from linuxfoundation, specifically: nats-server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-58251? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-33398

NamelessMC is website software for Minecraft servers. In version 2.2.4, `modules/Forum/pages/forum/get_quotes.php` only checks whether the caller is logged in, then …

CVE-2025-3013

Insecure Direct Object References (IDOR) in access control in Customer Portal before 2.1.4 on NightWolf Penetration Testing allows an attacker …

CVE-2025-3014

Insecure Direct Object References (IDOR) in access control in Tracking 2.1.4 on NightWolf Penetration Testing allows an attacker to access …

CVE-2025-27509

fleetdm/fleet is an open source device management, built on osquery. In vulnerable versions of Fleet, an attacker could craft a …

CVE-2024-26291

An Unauthenticated Arbitrary File Read vulnerability affects the Agent when installed on a system. The parameter filename does not validate …

CVE-2025-49594

XWiki OIDC has various tools to manipulate OpenID Connect protocol in XWiki. Starting in version 2.17.1 and prior to version …

CVE-2026-58251