{"id":"CVE-2026-27889","title":"NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system","summary":"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…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-190","CWE-1286"],"vendor":"linuxfoundation","product":"nats-server","affected":["nats-server >= 2.2.0, < 2.11.14","nats-server >= 2.12.0, < 2.12.5"],"patched":["nats-server 2.12.5"],"published":"2026-03-25","updated":"2026-09-09","sourceUpdated":"2026-09-09T13:19:10.343","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-27889","references":[{"url":"https://advisories.nats.io/CVE/secnote-2026-03.txt","label":"security-advisories@github.com"},{"url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6","label":"security-advisories@github.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:21769","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:22347","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23345","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/security/cve/CVE-2026-27889","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2451447","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889.json","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-27889"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27889"}],"tags":["nvd","cve.org","exploit-available","csaf","vex","red-hat"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"partial","timestamp":"2026-03-25T20:06:22.827675Z"},"epss":0.00582,"epssPercentile":0.46264,"ingestedAt":"2026-07-20T12:38:40.624Z","slug":"CVE-2026-27889","body":"## Overview\n\nNATS-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.\n\n## Affected\n\n- `nats-server >= 2.2.0, < 2.11.14`\n- `nats-server >= 2.12.0, < 2.12.5`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `nats-server 2.12.5`\n\n## Vendor advisories\n\n- **RHSA-2026:22347** · Red Hat · fixed in: Multicluster Global Hub 1.4.5 · released 2026-06-01 · [advisory](https://access.redhat.com/errata/RHSA-2026:22347)\n- **RHSA-2026:23345** · Red Hat · fixed in: Multicluster Global Hub 1.6.5 · released 2026-06-04 · [advisory](https://access.redhat.com/errata/RHSA-2026:23345)\n- **RHSA-2026:21769** · Red Hat · fixed in: Red Hat multicluster global hub 1.5.3 · released 2026-05-28 · [advisory](https://access.redhat.com/errata/RHSA-2026:21769)","depth":"midnight","depthScore":53,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":201487,"id":"CVE-2026-27889","ts":1789399510537,"field":"exploit_available","old":"false","new":"true"},{"seq":200221,"id":"CVE-2026-27889","ts":1789397084306,"field":"exploit_available","old":"true","new":"false"},{"seq":198145,"id":"CVE-2026-27889","ts":1789391732247,"field":"exploit_available","old":"false","new":"true"},{"seq":195938,"id":"CVE-2026-27889","ts":1789383397466,"field":"exploit_available","old":"true","new":"false"},{"seq":194867,"id":"CVE-2026-27889","ts":1789380300048,"field":"exploit_available","old":"false","new":"true"},{"seq":193654,"id":"CVE-2026-27889","ts":1789378266829,"field":"exploit_available","old":"true","new":"false"},{"seq":192441,"id":"CVE-2026-27889","ts":1789376232942,"field":"exploit_available","old":"false","new":"true"},{"seq":191228,"id":"CVE-2026-27889","ts":1789373124332,"field":"exploit_available","old":"true","new":"false"},{"seq":190013,"id":"CVE-2026-27889","ts":1789369120097,"field":"exploit_available","old":"false","new":"true"},{"seq":188800,"id":"CVE-2026-27889","ts":1789368035718,"field":"exploit_available","old":"true","new":"false"},{"seq":187583,"id":"CVE-2026-27889","ts":1789364994023,"field":"exploit_available","old":"false","new":"true"},{"seq":186370,"id":"CVE-2026-27889","ts":1789363000521,"field":"exploit_available","old":"true","new":"false"},{"seq":185156,"id":"CVE-2026-27889","ts":1789360965963,"field":"exploit_available","old":"false","new":"true"},{"seq":183943,"id":"CVE-2026-27889","ts":1789357941401,"field":"exploit_available","old":"true","new":"false"},{"seq":182195,"id":"CVE-2026-27889","ts":1789354093314,"field":"exploit_available","old":"false","new":"true"},{"seq":180988,"id":"CVE-2026-27889","ts":1789352941077,"field":"exploit_available","old":"true","new":"false"},{"seq":179781,"id":"CVE-2026-27889","ts":1789349993808,"field":"exploit_available","old":"false","new":"true"},{"seq":178574,"id":"CVE-2026-27889","ts":1789347809615,"field":"exploit_available","old":"true","new":"false"},{"seq":177367,"id":"CVE-2026-27889","ts":1789346175539,"field":"exploit_available","old":"false","new":"true"},{"seq":176160,"id":"CVE-2026-27889","ts":1789342749719,"field":"exploit_available","old":"true","new":"false"},{"seq":175944,"id":"CVE-2026-27889","ts":1789342356279,"field":"exploit_available","old":"false","new":"true"},{"seq":175484,"id":"CVE-2026-27889","ts":1789338387533,"field":"exploit_available","old":"true","new":"false"},{"seq":174279,"id":"CVE-2026-27889","ts":1789334597223,"field":"exploit_available","old":"false","new":"true"},{"seq":173074,"id":"CVE-2026-27889","ts":1789333197075,"field":"exploit_available","old":"true","new":"false"},{"seq":171888,"id":"CVE-2026-27889","ts":1789330878345,"field":"exploit_available","old":"false","new":"true"},{"seq":170702,"id":"CVE-2026-27889","ts":1789328396155,"field":"exploit_available","old":"true","new":"false"},{"seq":169497,"id":"CVE-2026-27889","ts":1789326903320,"field":"exploit_available","old":"false","new":"true"},{"seq":168292,"id":"CVE-2026-27889","ts":1789323440420,"field":"exploit_available","old":"true","new":"false"},{"seq":167087,"id":"CVE-2026-27889","ts":1789319370972,"field":"exploit_available","old":"false","new":"true"},{"seq":165882,"id":"CVE-2026-27889","ts":1789318279697,"field":"exploit_available","old":"true","new":"false"},{"seq":164677,"id":"CVE-2026-27889","ts":1789315538847,"field":"exploit_available","old":"false","new":"true"},{"seq":163472,"id":"CVE-2026-27889","ts":1789313260723,"field":"exploit_available","old":"true","new":"false"},{"seq":162267,"id":"CVE-2026-27889","ts":1789311710874,"field":"exploit_available","old":"false","new":"true"},{"seq":161062,"id":"CVE-2026-27889","ts":1789308262218,"field":"exploit_available","old":"true","new":"false"},{"seq":160567,"id":"CVE-2026-27889","ts":1789304190225,"field":"exploit_available","old":"false","new":"true"},{"seq":158405,"id":"CVE-2026-27889","ts":1789299282180,"field":"exploit_available","old":"true","new":"false"},{"seq":157369,"id":"CVE-2026-27889","ts":1789296462505,"field":"exploit_available","old":"false","new":"true"},{"seq":156164,"id":"CVE-2026-27889","ts":1789294383404,"field":"exploit_available","old":"true","new":"false"},{"seq":154959,"id":"CVE-2026-27889","ts":1789292637388,"field":"exploit_available","old":"false","new":"true"},{"seq":153754,"id":"CVE-2026-27889","ts":1789289346682,"field":"exploit_available","old":"true","new":"false"},{"seq":152966,"id":"CVE-2026-27889","ts":1789285257552,"field":"exploit_available","old":"false","new":"true"},{"seq":152210,"id":"CVE-2026-27889","ts":1789280963620,"field":"exploit_available","old":"true","new":"false"},{"seq":151171,"id":"CVE-2026-27889","ts":1789277459009,"field":"exploit_available","old":"false","new":"true"},{"seq":147900,"id":"CVE-2026-27889","ts":1789270879231,"field":"exploit_available","old":"true","new":"false"},{"seq":145940,"id":"CVE-2026-27889","ts":1789269174026,"field":"exploit_available","old":"false","new":"true"},{"seq":144843,"id":"CVE-2026-27889","ts":1789266105286,"field":"exploit_available","old":"true","new":"false"},{"seq":143747,"id":"CVE-2026-27889","ts":1789262439704,"field":"exploit_available","old":"false","new":"true"},{"seq":142583,"id":"CVE-2026-27889","ts":1789261190167,"field":"exploit_available","old":"true","new":"false"},{"seq":141419,"id":"CVE-2026-27889","ts":1789258611278,"field":"exploit_available","old":"false","new":"true"},{"seq":140221,"id":"CVE-2026-27889","ts":1789256401296,"field":"exploit_available","old":"true","new":"false"}]}