CVE-2026-33248
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system.
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/nats-io/nats-server/v2 | < 2.11.15 | 2.11.15 |
| go | github.com/nats-io/nats-server | > 0 | none recorded |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Linuxfoundation | Nats-Server | before 2.11.15 from 2.12.0 before 2.12.6 |