{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89561", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.725Z", "datePublished": "2026-09-11T19:44:32.822Z", "dateUpdated": "2026-10-21T12:47:51.427Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:47:51.427Z" }, "descriptions": [ { "lang": "en", "value": "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 \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 \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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - ipv6_rpl_srh_rcv() runs on the IPv6 local-delivery path (ipv6_rcv → ip6_protocol_deliver_rcu → ipv6_rthdr_rcv) for any unicast packet with Routing Header type 3; a remote attacker can deliver such packets over the network with no local access.\nAC:L - The attacker drives both sides of the race by flooding type-3 routing-header packets while concurrently dropping the ingress MTU below IPV6_MIN_MTU or deleting the netdev, and the window is large because ip6_rcv_core() drops RCU before extension-header processing.\nPR:N - Sending an unauthenticated IPv6 packet with a type-3 routing header requires no credentials; the NULL deref occurs before the rpl_seg_enabled check, and ip6_ptr teardown also occurs during ordinary container/veth lifecycle on shared hosts.\nUI:N - Exploitation needs only delivery of IPv6 routing-header packets during concurrent interface MTU/teardown; no victim action such as opening a file, mounting a filesystem, or clicking a link is required.\nS:U - A successful trigger oopses the same host kernel that processes the packet and does not cross a VM, hypervisor, IOMMU, or other security-authority boundary.\nC:N - The fault is a pure NULL pointer read of idev->cnf.rpl_seg_enabled at a fixed offset, causing an immediate page fault with no use-after-free, out-of-bounds read, or other information-disclosure primitive.\nI:N - This is a read-side NULL dereference only; there is no memory write, type confusion, or control-flow hijack primitive beyond crashing the kernel.\nA:H - The NULL dereference occurs in softirq context during IPv6 receive and produces a kernel oops or panic, as shown by the KASAN report in ipv6_rpl_srh_rcv, fully denying availability on the affected system." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/exthdrs.c" ], "versions": [ { "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3", "lessThan": "62b63a505c10e8db76017ef73c0b243e0dc5d288", "status": "affected", "versionType": "git" }, { "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3", "lessThan": "e7123e10c86eb88eaa90537dd1f232706de2d308", "status": "affected", "versionType": "git" }, { "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3", "lessThan": "63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c", "status": "affected", "versionType": "git" }, { "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3", "lessThan": "eab3a917cdcb182542a3aac6a0d2d30659ca9821", "status": "affected", "versionType": "git" }, { "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3", "lessThan": "f826df95332c07380206dbd54178b6eefb311aba", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/exthdrs.c" ], "versions": [ { "version": "5.7", "status": "affected" }, { "version": "0", "lessThan": "5.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/62b63a505c10e8db76017ef73c0b243e0dc5d288" }, { "url": "https://git.kernel.org/stable/c/e7123e10c86eb88eaa90537dd1f232706de2d308" }, { "url": "https://git.kernel.org/stable/c/63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c" }, { "url": "https://git.kernel.org/stable/c/eab3a917cdcb182542a3aac6a0d2d30659ca9821" }, { "url": "https://git.kernel.org/stable/c/f826df95332c07380206dbd54178b6eefb311aba" } ], "title": "ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()", "x_generator": { "engine": "bippy-1.2.0" } } } }