{"id":"CVE-2026-89563","title":"kernel: ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit() (CVE-2026-89563)","summary":"A flaw was found in the `ip6_tunnel` module of the Linux kernel. Incorrect handling of socket buffers (skb) during headroom reallocation in the `ip6_tnl_xmit()` function can lead to a double-free vulnerability. This occurs when an error pa…","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-1341","vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 8","enterprise_linux 9","openshift_container_platform 4","enterprise_linux 6"],"published":"2026-09-11","updated":"2026-09-18","sourceUpdated":"2026-09-18T22:00:45+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89563.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89563.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89563"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532305"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89563"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89563"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89563.mbox"},{"url":"https://git.kernel.org/stable/c/6e8eff8ed13b14708bc39f170144eacde494aac6"},{"url":"https://git.kernel.org/stable/c/dc1a319a4815c074914e2812e0e9cd0164ca682b"},{"url":"https://git.kernel.org/stable/c/629d5557e635cdbc109a14ed913ba5a540e3f79a"},{"url":"https://git.kernel.org/stable/c/defa0adeff132cc90ed66915b9a104d9393e1e54"},{"url":"https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74"},{"url":"https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"},{"url":"https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52"},{"url":"https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade"}],"tags":["csaf","vex","red-hat","cve.org"],"epss":0.00138,"epssPercentile":0.03603,"scores":{"vendor":7,"cna":7.8},"ingestedAt":"2026-09-14T15:23:07.451Z","slug":"CVE-2026-89563","body":"## Overview\n\nA flaw was found in the `ip6_tunnel` module of the Linux kernel. Incorrect handling of socket buffers (skb) during headroom reallocation in the `ip6_tnl_xmit()` function can lead to a double-free vulnerability. This occurs when an error path is taken after the original skb has been consumed, but the caller still holds a pointer to it, potentially allowing the same memory to be freed twice. This memory corruption issue could lead to a denial of service or potentially arbitrary code execution.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4, Red Hat Enterprise Linux 6 · 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 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89563.json)\n\n**kernel: ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()** — rated Important by Red Hat. Released 2026-09-11, updated 2026-09-18.\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- Red Hat Enterprise Linux 6\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 7\n\n## Remediation\n\nAffected","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":208102,"id":"CVE-2026-89563","ts":1789922708983,"field":"cvss","old":"7.8","new":"7"},{"seq":197920,"id":"CVE-2026-89563","ts":1789384320955,"field":"cvss","old":"4.4","new":"7.8"},{"seq":197919,"id":"CVE-2026-89563","ts":1789384320955,"field":"severity","old":"medium","new":"high"},{"seq":183463,"id":"CVE-2026-89563","ts":1789356675469,"field":"cvss","old":"7.8","new":"4.4"},{"seq":183462,"id":"CVE-2026-89563","ts":1789356675469,"field":"severity","old":"high","new":"medium"},{"seq":153378,"id":"CVE-2026-89563","ts":1789285350274,"field":"cvss","old":null,"new":"7.8"},{"seq":153377,"id":"CVE-2026-89563","ts":1789285350274,"field":"severity","old":"none","new":"high"},{"seq":147400,"id":"CVE-2026-89563","ts":1789270210762,"field":"cvss","old":null,"new":"4.4"},{"seq":147399,"id":"CVE-2026-89563","ts":1789270210762,"field":"severity","old":"none","new":"medium"},{"seq":109150,"id":"CVE-2026-89563","ts":1789183730509,"field":"cvss","old":null,"new":"4.4"},{"seq":109149,"id":"CVE-2026-89563","ts":1789183730509,"field":"severity","old":"none","new":"medium"}]}