{"cve":"CVE-2026-27889","nvd":{"published":"2026-03-25T20:16:27.210","modified":"2026-09-09T13:19:10.343","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-190","CWE-1286"],"references":["https://advisories.nats.io/CVE/secnote-2026-03.txt","https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6","https://access.redhat.com/errata/RHSA-2026:21769","https://access.redhat.com/errata/RHSA-2026:22347","https://access.redhat.com/errata/RHSA-2026:23345"],"products":["linuxfoundation:nats-server"],"source":"nvd","synced_at":"2026-10-19T22:28:18.033120106+00:00"},"epss":{"cve":"CVE-2026-27889","score":0.00593,"percentile":0.48347,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-pq2q-rcw4-3hr6","url":"https://osv.dev/vulnerability/GHSA-pq2q-rcw4-3hr6","summary":"NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead","modified":"2026-09-10T03:50:40.301051379Z","packages":[{"ecosystem":"Go","name":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","ranges":[">=2.2.0 <2.11.14"],"fixed":["2.11.14"]},{"ecosystem":"Go","name":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","ranges":[">=2.12.0 <2.12.5"],"fixed":["2.12.5"]},{"ecosystem":"Go","name":"github.com/nats-io/nats-server","purl":"pkg:golang/github.com/nats-io/nats-server","ranges":["all versions"],"fixed":[]}]},{"id":"GO-2026-4841","url":"https://osv.dev/vulnerability/GO-2026-4841","summary":"NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead in github.com/nats-io/nats-server","modified":"2026-03-27T14:14:21.538339Z","packages":[{"ecosystem":"Go","name":"github.com/nats-io/nats-server","purl":"pkg:golang/github.com/nats-io/nats-server","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","ranges":[">=2.2.0 <2.11.14",">=2.12.0 <2.12.5"],"fixed":["2.11.14","2.12.5"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}