CVE-2026-89561
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv() ipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL check when reading idev->cnf.rpl_seg_enabled. When the device's MTU drops below IPV6_MIN_MTU, addrconf_ifdown() clears dev->ip6_ptr through RCU_INIT_POINTER(). A packet that passed the idev check in ip6_rcv_core() can then reach ipv6_rpl_srh_rcv() with dev->ip6_ptr already NULL. Reproduced by flooding the receiving interface with ping6 traffic while flapping its MTU between 1500 and 1200: BUG: KASAN: null-ptr-deref in ipv6_rpl_srh_rcv+0xb3/0x1070 Read of size 4 at addr 00000000000006b4 by task ping6/394 CPU: 2 UID: 0 PID: 394 Comm: ping6 Not tainted 7.2.0-rc7-micro-vm-dev-00095-g24ef02f934ee #240 PREEMPT(full) Call Trace: <IRQ> kasan_report+0xc6/0x100 ipv6_rpl_srh_rcv+0xb3/0x1070 ip6_protocol_deliver_rcu+0x759/0x9a0 ip6_input_finish+0xa8/0x1b0 ip6_input+0xe1/0x490 ipv6_rcv+0x33d/0x460 __netif_receive_skb_one_core+0xd6/0x130 process_backlog+0x2cc/0xa00 __napi_poll.constprop.0+0x56/0x270 net_rx_action+0x327/0x730 handle_softirqs+0x11e/0x630 do_softirq+0xb3/0xf0 </IRQ> Both ipv6_rpl_srh_rcv() and ipv6_srh_rcv() are called only from ipv6_rthdr_rcv(), which already has an idev lookup. Fix the NULL dereference on the RPL path by checking idev in ipv6_rthdr_rcv(), before it calls either function. The callees take idev as an argument and no longer call __in6_dev_get(), so the packet is now dropped in one place, with SKB_DROP_REASON_IPV6DISABLED on both paths.
View original CVE JSON
{
"id": "CVE-2026-89561",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-11T20:19:39.933",
"lastModified": "2026-10-30T13:20:21.740",
"vulnStatus": "Received",
"cveTags": [],
"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 <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."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/ipv6/exthdrs.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
"lessThan": "f5e89dfc0a815c6ed12791d8deb3b6f39dd0621e",
"versionType": "git",
"status": "affected"
},
{
"version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
"lessThan": "62b63a505c10e8db76017ef73c0b243e0dc5d288",
"versionType": "git",
"status": "affected"
},
{
"version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
"lessThan": "e7123e10c86eb88eaa90537dd1f232706de2d308",
"versionType": "git",
"status": "affected"
},
{
"version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
"lessThan": "63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c",
"versionType": "git",
"status": "affected"
},
{
"version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
"lessThan": "eab3a917cdcb182542a3aac6a0d2d30659ca9821",
"versionType": "git",
"status": "affected"
},
{
"version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
"lessThan": "f826df95332c07380206dbd54178b6eefb311aba",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/ipv6/exthdrs.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "5.7",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.7",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.191",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.160",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.111",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.50",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.4",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"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",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 3.9,
"impactScore": 3.6
}
]
},
"references": [
{
"url": "https://git.kernel.org/stable/c/62b63a505c10e8db76017ef73c0b243e0dc5d288",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e7123e10c86eb88eaa90537dd1f232706de2d308",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/eab3a917cdcb182542a3aac6a0d2d30659ca9821",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f5e89dfc0a815c6ed12791d8deb3b6f39dd0621e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f826df95332c07380206dbd54178b6eefb311aba",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}