CVE-2026-58252: 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 could receive messages on denied subjects when a wildcard subscription overlapped with a configured wildcard deny rule but was not a subset of it, and queue subscriptions could also affect delivery to legitimate queue consumers. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.

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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

0.0047

Probability of exploitation

0.38%

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/8ced85a11497f86704a95d960281480ce037386b https://github.com/nats-io/nats-server/commit/a42a6d1e258eb5c3a2190384d31965a4b715e854 https://github.com/nats-io/nats-server/commit/e611ca9604697b02d8f22beb76037400a9cf72e6 https://github.com/nats-io/nats-server/security/advisories/GHSA-wh7g-5m82-pmhr

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-2026-58252? +

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 could receive messages on denied subjects when a wildcard subscription overlapped with a configured wildcard deny rule but was not a subset of it, and queue subscriptions could also affect delivery to legitimate queue consumers. 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-2026-58252? +

CVE-2026-58252 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 0.0047, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-58252? +

CVE-2026-58252 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-2026-58252? +

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.

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