{"id":"JLSEC-2026-1121","details":"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.","modified":"2026-08-03T19:15:03.761954394Z","published":"2026-08-03T19:08:57.739Z","upstream":["CVE-2026-27889"],"database_specific":{"license":"CC-BY-4.0","sources":[{"imported":"2026-08-03T18:16:26.994Z","modified":"2026-08-03T13:17:36.973Z","published":"2026-03-25T20:16:27.210Z","url":"https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-27889","html_url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27889","database_specific":{"status":"Modified"},"id":"CVE-2026-27889"}]},"references":[{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:21769"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:22347"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:23345"},{"type":"WEB","url":"https://access.redhat.com/security/cve/CVE-2026-27889"},{"type":"WEB","url":"https://advisories.nats.io/CVE/secnote-2026-03.txt"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2451447"},{"type":"WEB","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889.json"}],"affected":[{"package":{"name":"nats_server_jll","ecosystem":"Julia","purl":"pkg:julia/nats_server_jll?uuid=8b1691f7-6002-537d-bdf7-c6203599dc08"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.14.3+0"}]}],"database_specific":{"source":"https://github.com/JuliaLang/SecurityAdvisories.jl/tree/generated/osv/2026/JLSEC-2026-1121.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}