CVE-2026-27571
5.9 · MEDIUMOverview
CVE-2026-27571 is a medium-severity vulnerability affecting linuxfoundation nats-server. It was published on February 24, 2026 and has a CVSS 3.1 base score of 5.9 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. 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. The WebSockets handling of NATS messages handles compressed messages via the WebSockets negotiated compression. Prior to versions 2.11.2 and 2.12.3, the implementation bound the memory size of a NATS message but did not independently bound the memory consumption of the memory stream when constructing a NATS message which might then fail validation for size reasons. An attacker can use a compression bomb to cause excessive memory consumption, often resulting in the operating system terminating the server process. The use of compression is negotiated before authentication, so this does not require valid NATS credentials to exploit. The fix, present in versions 2.11.2 and 2.12.3, was to bounds the decompression to fail once the message was too large, instead of continuing on. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-point
Remediation
Check the references section for vendor advisories and patches from linuxfoundation. Update nats-server to the latest patched version. 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.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| linuxfoundation | nats-server | >= 0, < 2.11.12 | Affected |
Frequently Asked Questions
What is CVE-2026-27571?
CVE-2026-27571 is a medium-severity vulnerability affecting linuxfoundation nats-server. It was published on February 24, 2026 and has a CVSS 3.1 base score of 5.9 (MEDIUM).
How severe is CVE-2026-27571?
This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-27571?
Check the references section for vendor advisories and patches from linuxfoundation. Update nats-server to the latest patched version. 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-2026-27571?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-27571 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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