CVE-2026-33248 (GCVE-0-2026-33248)

Vulnerability from cvelistv5 – Published: 2026-03-25 20:18 – Updated: 2026-03-26 19:52
VLAI?
Title
NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching
Summary
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.
Severity ?
4.2 (Medium)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
CWE
  • CWE-287 - Improper Authentication
  • CWE-295 - Improper Certificate Validation
Assigner
References
Impacted products
Vendor Product Version
nats-io nats-server Affected: < 2.11.15
Affected: >= 2.12.0-RC.1, < 2.12.6
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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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