cbcvebase.
CVE-2026-33248
published 2026-03-25

CVE-2026-33248: 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…

PriorityP425medium4.2CVSS 3.1
AVNACHPRLUINSUCLILAN
EPSS
0.14%
3.9th 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.

Affected

8 ranges
VendorProductVersion rangeFixed in
debiannats-server< nats-server 2.12.6-1 (forky)nats-server 2.12.6-1 (forky)
github.comnats-io_nats-server_v2>= 0 < 2.11.152.11.15
github.comnats-io_nats-server_v2>= 2.12.0-RC.1 < 2.12.62.12.6
linuxfoundationnats-server< 2.11.152.11.15
linuxfoundationnats-server>= 0 < 2.12.6-12.12.6-1
linuxfoundationnats-server>= 2.12.0 < 2.12.62.12.6
nats-ionats-server< 2.11.152.11.15
nats-ionats-server——

CVSS provenance

nvdv3.14.2MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
osv4.2MEDIUM
vendor_debian4.2MEDIUM
vendor_redhat4.2MEDIUM
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