How severe is CVE-2026-33218?

CVE-2026-33218 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-33218 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33218?

CVE-2026-33218 affects Linuxfoundation Nats-server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33218?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-33218 have an EU (EUVD) identifier?

Yes. CVE-2026-33218 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-15968.

When was CVE-2026-33218 published?

CVE-2026-33218 was published on 2026-03-25 and last updated on 2026-06-30.

CVE-2026-33218

CVE-2026-33218 is a high-severity vulnerability in Linuxfoundation Nats-server with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 1% (45th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-15968
Weakness: CWE-20
Affected product: Linuxfoundation Nats-server
Published: 2026-03-25
Last modified: 2026-06-30

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, a client which can connect to the leafnode port can crash the nats-server with a certain malformed message pre-authentication. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable leafnode support if not needed or restrict network connections to the leafnode port, if plausible without compromising the service offered.

Frequently asked questions

What is CVE-2026-33218?: 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, a client which can connect to the leafnode port can crash the nats-server with a certain malformed message pre-authentication. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable leafnode support if not needed or restrict network connections to the leafnode port, if plausible without compromising the service offered.
How severe is CVE-2026-33218?: CVE-2026-33218 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-33218 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (45th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33218?: CVE-2026-33218 affects Linuxfoundation Nats-server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33218?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-33218 have an EU (EUVD) identifier?: Yes. CVE-2026-33218 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-15968.
When was CVE-2026-33218 published?: CVE-2026-33218 was published on 2026-03-25 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*

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