{"cve":"CVE-2026-89561","nvd":{"published":"2026-09-11T20:19:39.933","modified":"2026-10-21T13:20:08.500","status":"Received","description":"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_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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":[],"references":["https://git.kernel.org/stable/c/62b63a505c10e8db76017ef73c0b243e0dc5d288","https://git.kernel.org/stable/c/63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c","https://git.kernel.org/stable/c/e7123e10c86eb88eaa90537dd1f232706de2d308","https://git.kernel.org/stable/c/eab3a917cdcb182542a3aac6a0d2d30659ca9821","https://git.kernel.org/stable/c/f826df95332c07380206dbd54178b6eefb311aba"],"products":[],"source":"nvd","synced_at":"2026-10-22T16:41:11.231219466+00:00"},"epss":{"cve":"CVE-2026-89561","score":0.00441,"percentile":0.38,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}