Is CVE-2026-33248 in the CISA KEV catalog?

No. CVE-2026-33248 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-33248?

CVE-2026-33248 has a CVSS v3 base score of 4.2 (MEDIUM).

What is the EPSS score for CVE-2026-33248?

CVE-2026-33248 has an EPSS score of 0.14% (4th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-33248?

Upgrade nats-server on debian unstable to 2.12.6-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-33248

MEDIUM

4.2

CVSS v3

NVD

Description

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.

CWE-287Improper Authentication CWE-295Improper Certificate Validation

How to fix

Remediation Available

nats-serverDebian

Fixed in:2.12.6-1CVE-2026-33248

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

Exploit Intelligence

0.14%probability of exploitation in 30 days

4thpercentile

Low risk: more likely to be exploited than 4% of all known CVEs.

References

Vendor Advisory2

Related Vulnerabilities

Other CWE-287 (Improper Authentication) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-35082	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-35078	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2017-7921	Critical	9.8	100%	KEV	-
CVE-2024-7593	Critical	9.8	100%	KEV	-
CVE-2023-46805	High	8.2	100%	KEV + Ransom	-
CVE-2022-40684	Critical	9.8	100%	KEV + Ransom	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-26.