CVE catalog

CVE-2026-33248

Severity: Medium · CVSS 4.8CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Published: Mar 24, 2026, 11:00:00 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.15% · Oct 25, 2026

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.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	nats-server	sid	`2.15.1-1`	fixed
Debian	nats-server	forky	`2.15.1-1`	fixed
Debian	nats-server	trixie	`2.10.27-1`	vulnerable
Debian	nats-server	bookworm	`2.9.10-1`	vulnerable
Go	github.com/nats-io/nats-server/v2	Not reported	`2.11.15`	fixed
Go	github.com/nats-io/nats-server/v2	Not reported	`2.12.6`	fixed
Cpe	nats-server	Not reported	Not reported	vulnerable
Cpe	nats-server	Not reported	`2.11.15`	fixed
Cpe	nats-server	Not reported	`2.12.6`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	nats-server	source	sid	`2.12.6-1`	not yet assigned	Not reported	Not reported
Debian	nats-server	source	forky	`2.12.6-1`	not yet assigned	Not reported	Not reported
Debian	nats-server	source	trixie	`(unfixed)`	not yet assigned	Not reported	Not reported
Debian	nats-server	source	bookworm	`(unfixed)`	not yet assigned	Not reported	Not reported
Go	github.com/nats-io/nats-server/v2	go	Not reported	`2.11.15`	Not reported	Not reported	Not reported
Go	github.com/nats-io/nats-server/v2	go	Not reported	`2.12.6`	Not reported	Not reported	Not reported
Cpe	nats-server	cpe	Not reported	`2.11.15`	Not reported	Not reported	Not reported
Cpe	nats-server	cpe	Not reported	`2.12.6`	Not reported	Not reported	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[golang-github-nats-io-nats-server-dev]Affected
Source package: [nats-server]
Details (2)
- 2.9.10-1 · all · bookworm
  Affected
  nvd · nats-server · debian · bookworm; nvd · nats-server · debian · 12
- 2.9.10-1 · all · bookworm
  Affected
  nvd · nats-server · debian · bookworm; nvd · nats-server · debian · 12
[nats-server]Affected
Source package: [nats-server]
Details (2)
- 2.9.10-1+b3 · amd64 · bookworm
  Affected
  nvd · nats-server · debian · bookworm; nvd · nats-server · debian · 12
- 2.9.10-1+b3 · arm64 · bookworm
  Affected
  nvd · nats-server · debian · bookworm; nvd · nats-server · debian · 12

[Debian 13 (Trixie)]

[golang-github-nats-io-nats-server-dev]Affected
Source package: [nats-server]
Details (2)
- 2.10.27-1 · all · trixie
  Affected
  nvd · nats-server · debian · 13
- 2.10.27-1 · all · trixie
  Affected
  nvd · nats-server · debian · 13
[nats-server]Affected
Source package: [nats-server]
Details (2)
- 2.10.27-1+b2 · amd64 · trixie
  Affected
  nvd · nats-server · debian · 13
- 2.10.27-1+b2 · arm64 · trixie
  Affected
  nvd · nats-server · debian · 13

Observed: Oct 23, 2026, 10:39:01 PM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]