How severe is CVE-2026-33249?

CVE-2026-33249 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-33249 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-33249?

CVE-2026-33249 affects Linuxfoundation Nats-server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-33249?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-33249 have an EU (EUVD) identifier?

Yes. CVE-2026-33249 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16000.

When was CVE-2026-33249 published?

CVE-2026-33249 was published on 2026-03-25 and last updated on 2026-06-17.

CVE-2026-33249

CVE-2026-33249 is a medium-severity vulnerability in Linuxfoundation Nats-server with a CVSS 3.x base score of 4.3. 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-863.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (14th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-16000
Weakness: CWE-863
Affected product: Linuxfoundation Nats-server
Published: 2026-03-25
Last modified: 2026-06-17

Description

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, a valid client which uses message tracing headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to which the client does not have publish permission. The payload is a valid trace message and not chosen by the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

Frequently asked questions

What is CVE-2026-33249?: NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, a valid client which uses message tracing headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to which the client does not have publish permission. The payload is a valid trace message and not chosen by the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
How severe is CVE-2026-33249?: CVE-2026-33249 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-33249 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-33249?: CVE-2026-33249 affects Linuxfoundation Nats-server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-33249?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-33249 have an EU (EUVD) identifier?: Yes. CVE-2026-33249 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-16000.
When was CVE-2026-33249 published?: CVE-2026-33249 was published on 2026-03-25 and last updated on 2026-06-17.

References

Affected products (1)

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

More vulnerabilities in Linuxfoundation Nats-server

CVE-2022-28357 — Critical (CVSS 9.8): NATS nats-server 2.2.0 through 2.7.4 allows directory traversal because of an unintended path to a management action…
CVE-2020-26892 — Critical (CVSS 9.8): The JWT library in NATS nats-server before 2.1.9 has Incorrect Access Control because of how expired credentials are…
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CVE-2026-33216 — High (CVSS 8.6): NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions…
CVE-2026-33218 — High (CVSS 7.5): NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions…
CVE-2026-29785 — High (CVSS 7.5): NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions…

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