{"id":"JLSEC-2026-1127","details":"NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, a malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data. This is a milder variant of CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment.","modified":"2026-08-03T19:15:03.819785440Z","published":"2026-08-03T19:08:57.739Z","upstream":["CVE-2026-33219"],"database_specific":{"license":"CC-BY-4.0","sources":[{"modified":"2026-08-03T13:17:53.537Z","published":"2026-03-25T20:16:32.777Z","url":"https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33219","html_url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33219","database_specific":{"status":"Modified"},"id":"CVE-2026-33219","imported":"2026-08-03T18:16:27.186Z"}]},"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-2026-33219"},{"type":"WEB","url":"https://advisories.nats.io/CVE/secnote-2026-02.txt"},{"type":"WEB","url":"https://advisories.nats.io/CVE/secnote-2026-11.txt"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2451445"},{"type":"WEB","url":"https://github.com/advisories/GHSA-qrvq-68c2-7grw"},{"type":"WEB","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33219.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-2026-1127.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:L"}]}