ipv6: Fix out-of-bound access in fib6_add_rt2node().

{
  "id": "dd32bdaa065e83d825eefd934eb9ba514c57deac31a82155c84a8515e3c9a2a0",
  "url": "https://osv.dev/vulnerability/CVE-2026-46260",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ipv6: Fix out-of-bound access in fib6_add_rt2node().",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix out-of-bound access in fib6_add_rt2node(). syzbot reported out-of-bound read in fib6_add_rt2node(). [0] When IPv6 route is created with RTA_NH_ID, struct fib6_info does not have the trailing struct fib6_nh. The cited commit started to check !iter->fib6_nh->fib_nh_gw_family to ensure that rt6_qualify_for_ecmp() will return false for iter. If iter->nh is not NULL, rt6_qualify_for_ecmp() returns false anyway. Let's check iter->nh before reading iter->fib6_nh and avoid OOB read. [0]: BUG: KASAN: slab-out-of-bounds in fib6_add_rt2node+0x349c/0x3500 net/ipv6/ip6_fib.c:1142 Read of size 1 at addr ffff8880384ba6de by task syz.0.18/5500 CPU: 0 UID: 0 PID: 5500 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 fib6_add_rt2node+0x349c/0x3500 net/ipv6/ip6_fib.c:1142 fib6_add_rt2node_nh net/ipv6/ip6_fib.c:1363 [inline] fib6_add+0x910/0x18c0 net/ipv6/ip6_fib.c:1531 __ip6_ins_rt net/ipv6/route.c:1351 [inline] ip6_route_add+0xde/0x1b0 net/ipv6/route.c:3957 inet6_rtm_newroute+0x268/0x19e0 net/ipv6/route.c:5660 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6958 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:",
    "evidence": "osv:CVE-2026-46260",
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    "severity": "high",
    "structured": {
      "id": "CVE-2026-46260",
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          "type": "CVSS_V3",
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      "modified": "2026-10-28T02:30:26.456588647Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/03b5051e02f5a3772eee57493ad697d4b505b0c2",
        "https://git.kernel.org/stable/c/500e54615c97bc3c427e52305a6fcd38a0e008a3",
        "https://git.kernel.org/stable/c/8244f959e2c125c849e569f5b23ed49804cce695",
        "https://git.kernel.org/stable/c/bcc60ad129ae1837cf809c81bff56ec8bfdb6b11",
        "https://git.kernel.org/stable/c/bf5009a06e03ee9a51052bb59f2228a5e4e66260",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46260.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46260",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46260.json"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 492702,
  "published_at": "2026-06-03T15:49:57.561+00:00"
}