{"id":"CVE-2026-89561","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()\n\nipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL\ncheck when reading idev->cnf.rpl…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()\n\nipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL\ncheck when reading idev->cnf.rpl…","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-476"],"vendor":"Linux","product":"Linux","affected":["Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 < e7123e10c86eb88eaa90537dd1f232706de2d308","Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 < 63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c","Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 < eab3a917cdcb182542a3aac6a0d2d30659ca9821","Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 < f826df95332c07380206dbd54178b6eefb311aba","Linux 5.7"],"published":"2026-09-11","updated":"2026-09-21","sourceUpdated":"2026-09-21T14:17:23.290","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89561","references":[{"url":"https://git.kernel.org/stable/c/63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e7123e10c86eb88eaa90537dd1f232706de2d308","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/eab3a917cdcb182542a3aac6a0d2d30659ca9821","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f826df95332c07380206dbd54178b6eefb311aba","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89561.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89561"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532448"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89561"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89561"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89561.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00432,"epssPercentile":0.36847,"scores":{"nvd":7.5,"cna":7.5,"vendor":5.5},"ingestedAt":"2026-09-14T15:23:07.474Z","slug":"CVE-2026-89561","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()\n\nipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL\ncheck when reading idev->cnf.rpl_seg_enabled.\n\nWhen the device's MTU drops below IPV6_MIN_MTU, addrconf_ifdown() clears\ndev->ip6_ptr through RCU_INIT_POINTER(). A packet that passed the idev\ncheck in ip6_rcv_core() can then reach ipv6_rpl_srh_rcv() with\ndev->ip6_ptr already NULL.\n\nReproduced by flooding the receiving interface with ping6 traffic while\nflapping its MTU between 1500 and 1200:\n\n BUG: KASAN: null-ptr-deref in ipv6_rpl_srh_rcv+0xb3/0x1070\n Read of size 4 at addr 00000000000006b4 by task ping6/394\n\n CPU: 2 UID: 0 PID: 394 Comm: ping6 Not tainted 7.2.0-rc7-micro-vm-dev-00095-g24ef02f934ee #240 PREEMPT(full)\n Call Trace:\n  <IRQ>\n  kasan_report+0xc6/0x100\n  ipv6_rpl_srh_rcv+0xb3/0x1070\n  ip6_protocol_deliver_rcu+0x759/0x9a0\n  ip6_input_finish+0xa8/0x1b0\n  ip6_input+0xe1/0x490\n  ipv6_rcv+0x33d/0x460\n  __netif_receive_skb_one_core+0xd6/0x130\n  process_backlog+0x2cc/0xa00\n  __napi_poll.constprop.0+0x56/0x270\n  net_rx_action+0x327/0x730\n  handle_softirqs+0x11e/0x630\n  do_softirq+0xb3/0xf0\n  </IRQ>\n\nBoth ipv6_rpl_srh_rcv() and ipv6_srh_rcv() are called only from\nipv6_rthdr_rcv(), which already has an idev lookup.\n\nFix the NULL dereference on the RPL path by checking idev in\nipv6_rthdr_rcv(), before it calls either function. The callees take idev as\nan argument and no longer call __in6_dev_get(), so the packet is now\ndropped in one place, with SKB_DROP_REASON_IPV6DISABLED on both paths.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89561.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":208387,"id":"CVE-2026-89561","ts":1789997915404,"field":"cvss","old":"5.5","new":"7.5"},{"seq":208386,"id":"CVE-2026-89561","ts":1789997915404,"field":"severity","old":"medium","new":"high"},{"seq":203858,"id":"CVE-2026-89561","ts":1789490210222,"field":"cvss","old":"5.9","new":"5.5"},{"seq":202881,"id":"CVE-2026-89561","ts":1789403732790,"field":"cvss","old":"7.5","new":"5.9"},{"seq":202880,"id":"CVE-2026-89561","ts":1789403732790,"field":"severity","old":"high","new":"medium"},{"seq":197916,"id":"CVE-2026-89561","ts":1789384320940,"field":"cvss","old":"5.9","new":"7.5"},{"seq":197915,"id":"CVE-2026-89561","ts":1789384320940,"field":"severity","old":"medium","new":"high"},{"seq":183465,"id":"CVE-2026-89561","ts":1789356675477,"field":"cvss","old":"7.5","new":"5.9"},{"seq":183464,"id":"CVE-2026-89561","ts":1789356675477,"field":"severity","old":"high","new":"medium"},{"seq":153374,"id":"CVE-2026-89561","ts":1789285350259,"field":"cvss","old":null,"new":"7.5"},{"seq":153373,"id":"CVE-2026-89561","ts":1789285350259,"field":"severity","old":"none","new":"high"},{"seq":147177,"id":"CVE-2026-89561","ts":1789270199139,"field":"cvss","old":null,"new":"5.9"},{"seq":147176,"id":"CVE-2026-89561","ts":1789270199139,"field":"severity","old":"none","new":"medium"},{"seq":108934,"id":"CVE-2026-89561","ts":1789183729612,"field":"cvss","old":null,"new":"5.9"},{"seq":108933,"id":"CVE-2026-89561","ts":1789183729612,"field":"severity","old":"none","new":"medium"}]}