CVE-2026-33248

nats-server: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system

CVE-2026-33248 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-33248, released March 25, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine
CVSS
4.2
medium
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0015
4th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Linux
govulncheck-vulndb · opensuse-leap 15.6 0.0.20260326T203309-150000.1.155.2 SUSE-SU-2026:1135-1 Mar 27, 2026
govulncheck-vulndb · opensuse-leap 16.0 0.0.20260723T184607-160000.1.1 OPENSUSE-SU-2026:21483-1 Jul 30, 2026
nats-server · Debian 14 2.12.6-1 DEBIAN-CVE-2026-33248 Mar 25, 2026

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