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CVE-2026-27889

7.5 · HIGH

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system.

Published Mar 25, 2026CWE-190EPSS 0.84%

Overview

CVE-2026-27889 is a high-severity vulnerability. It was published on March 25, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server. This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refadvisories.nats.io/CVE/secnote-2026-03.txtGitHubgithub.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6Refaccess.redhat.com/errata/RHSA-2026:21769Refaccess.redhat.com/errata/RHSA-2026:22347Refaccess.redhat.com/errata/RHSA-2026:23345Refaccess.redhat.com/security/cve/CVE-2026-27889Refbugzilla.redhat.com/show_bug.cgi?id=2451447Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-27889?

CVE-2026-27889 is a high-severity vulnerability. It was published on March 25, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-27889?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-27889?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-27889?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-27889 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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