CVE•Published 2026-03-25•Modified 2026-06-30•0 articles on news•7 live references•NVD data

CVE-2026-27889Linuxfoundation · Nats-server

Vulnerability data via NVD (ingested)

CVSS v3.1

7.5

HIGH

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

EPSS percentile

—

Weaknesses (CWE)

CWE-190Integer Overflow or Wraparound CWE-1286Improper Validation of Syntactic Correctness of Input

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.

Timeline

Published 2026-03-25

Modified 2026-06-30

External references

NVD MITRE Exploit-DB GitHub PoC Sploitus trickest/cve VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-27889

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Linuxfoundation Nats-server"

All exposed Linuxfoundation Nats-server instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Nats-server"

HTTP body or banner mentions "Nats-server" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-27889