{"id":"CVE-2026-89476","title":"kernel: sctp: fix stream->outcnt underflow on duplicate RECONF responses (CVE-2026-89476)","summary":"A flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation. A remote attacker could exploit this by sending specially crafted duplicate RECONF responses. This action can cause an underflow in the `str…","severity":"high","cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"vendor","cwe":"CWE-191","vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 8","enterprise_linux 9","openshift_container_platform 4"],"published":"2026-09-11","updated":"2026-09-14","sourceUpdated":"2026-09-14T15:20:33+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89476.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89476.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89476"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532035"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89476"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89476"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89476.mbox"},{"url":"https://git.kernel.org/stable/c/041f7df5a929d3e7435dd8387e8ea17f2d412b7d"},{"url":"https://git.kernel.org/stable/c/59f61c39cb99ee1737bd742a20094fe5653389bb"},{"url":"https://git.kernel.org/stable/c/793519e343867ee9a3e84f6cac07f81f2aec7b5d"},{"url":"https://git.kernel.org/stable/c/092acd3c55a4077b00489064615d8d2d898daf91"},{"url":"https://git.kernel.org/stable/c/2d867663c563e8009257b9edf9c8ec75d9bbf19a"},{"url":"https://git.kernel.org/stable/c/d02a5794c3deedcb8476d017fcee2b7aaedab2e1"},{"url":"https://git.kernel.org/stable/c/8320cbd81bc21a1ca6ebdf70ad610ebc5ef1bd68"},{"url":"https://git.kernel.org/stable/c/3faf13aff243ca9f78d08b1a2956ef5a6fc77b6e"}],"tags":["csaf","vex","red-hat","cve.org"],"epss":0.00686,"epssPercentile":0.50814,"scores":{"vendor":7,"cna":7.5},"ingestedAt":"2026-09-14T15:23:07.453Z","slug":"CVE-2026-89476","body":"## Overview\n\nA flaw was found in the Linux kernel's Stream Control Transmission Protocol (SCTP) implementation. A remote attacker could exploit this by sending specially crafted duplicate RECONF responses. This action can cause an underflow in the `stream->outcnt` counter, potentially leading to unexpected system behavior or a denial of service (DoS) condition.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89476.json)\n\n**kernel: sctp: fix stream->outcnt underflow on duplicate RECONF responses** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-14.\n\nAffected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\nNo fix planned:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 8\n- Red Hat Enterprise Linux 9\n- Red Hat OpenShift Container Platform 4\n\nNot affected:\n\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 7\n\n## Remediation\n\nAffected","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":202756,"id":"CVE-2026-89476","ts":1789403715646,"field":"cvss","old":"7.5","new":"7"},{"seq":198034,"id":"CVE-2026-89476","ts":1789384321481,"field":"cvss","old":"5.9","new":"7.5"},{"seq":198033,"id":"CVE-2026-89476","ts":1789384321481,"field":"severity","old":"medium","new":"high"},{"seq":183788,"id":"CVE-2026-89476","ts":1789356677393,"field":"cvss","old":"7.5","new":"5.9"},{"seq":183787,"id":"CVE-2026-89476","ts":1789356677393,"field":"severity","old":"high","new":"medium"},{"seq":153252,"id":"CVE-2026-89476","ts":1789285349747,"field":"cvss","old":null,"new":"7.5"},{"seq":153251,"id":"CVE-2026-89476","ts":1789285349747,"field":"severity","old":"none","new":"high"},{"seq":109650,"id":"CVE-2026-89476","ts":1789183732790,"field":"cvss","old":null,"new":"5.9"},{"seq":109649,"id":"CVE-2026-89476","ts":1789183732790,"field":"severity","old":"none","new":"medium"}]}