CVE-2026-33248

4.2 MEDIUM 0.1% exploit odds Fix listed Auth & access Browser & mail

What it is

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, when using mTLS for client identity, with `verify_and_map` to derive a NATS identity from the client certificate's Subject DN, certain patterns of RDN would not be correctly enforced, allowing for authentication bypass. This does require a valid certificate from a CA already trusted for client certificates, and `DN` naming patterns which the NATS maintainers consider highly unlikely. So this is an unlikely attack. Nonetheless, administrators who have been very sophisticated in their `DN` construction patterns might conceivably be impacted. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, developers should review their CA issuing practices.

At a glance

Exploitability: Can be exploited over the network with a low-privilege account. Limited direct impact.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-03-25 21:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 10:37 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 4.2 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-03-25 21:16 UTC
Last modified: 2026-06-17 10:37 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Weakness: CWE-287 · Improper authentication
Record status: Analyzed

Affected

Linuxfoundation nats-server < 2.11.15
Linuxfoundation nats-server < 2.12.6

Attack profile CVSS 3.1 · 4.2

Attack vector: Network
Complexity: High
Privileges needed: Low
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-33248.md and follow it. Check whether this project is affected by CVE-2026-33248. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record