CVE-2026-74562 (GCVE-0-2026-74562)
Vulnerability from cvelistv5
Published
2026-08-15 12:28
Modified
2026-08-17 05:48
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
nexthop: take nh->lock for f6i_list walks in replace check and notify
fib6_check_nh_list() and __nexthop_replace_notify() walk nh->f6i_list
during an RTNL-serialized nexthop replace without holding nh->lock. IPv6
RTM_NEWROUTE/RTM_DELROUTE run without RTNL and mutate that list under
nh->lock (fib6_add_rt2node_nh(), fib6_purge_rt()), so both walks race a
concurrent route delete that unlinks and frees a fib6_info:
BUG: KASAN: slab-use-after-free in rt6_fill_node.isra.0 (net/ipv6/route.c:5799)
Read of size 4 at addr ffff888014607e64 by task exploit/143
rt6_fill_node.isra.0 (net/ipv6/route.c:5799)
fib6_rt_update (net/ipv6/route.c:6412)
__nexthop_replace_notify (net/ipv4/nexthop.c:2542)
rtm_new_nexthop (net/ipv4/nexthop.c:2554)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)
BUG: KASAN: slab-use-after-free in fib6_check_nh_list (net/ipv4/nexthop.c:1605)
Read of size 8 at addr ffff888014a7d068 by task exploit/142
fib6_check_nh_list (net/ipv4/nexthop.c:1605)
rtm_new_nexthop (net/ipv4/nexthop.c:2575)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)
Both walks only read the entries and take no tb6_lock, so protect them
with nh->lock; fib6_rt_update() uses gfp_any(), which returns GFP_ATOMIC
under the lock.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv4/nexthop.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "bb2b072c619c1f741a6234257050f72005dc63ef",
"status": "affected",
"version": "081efd18326e353c6fbfdeff903a83edde953f72",
"versionType": "git"
},
{
"lessThan": "072cd1f21819dedd2252e704d255de3b0cfc61a7",
"status": "affected",
"version": "081efd18326e353c6fbfdeff903a83edde953f72",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv4/nexthop.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.16"
},
{
"lessThan": "6.16",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.8",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.8",
"versionStartIncluding": "6.16",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "6.16",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: take nh-\u003elock for f6i_list walks in replace check and notify\n\nfib6_check_nh_list() and __nexthop_replace_notify() walk nh-\u003ef6i_list\nduring an RTNL-serialized nexthop replace without holding nh-\u003elock. IPv6\nRTM_NEWROUTE/RTM_DELROUTE run without RTNL and mutate that list under\nnh-\u003elock (fib6_add_rt2node_nh(), fib6_purge_rt()), so both walks race a\nconcurrent route delete that unlinks and frees a fib6_info:\n\n BUG: KASAN: slab-use-after-free in rt6_fill_node.isra.0 (net/ipv6/route.c:5799)\n Read of size 4 at addr ffff888014607e64 by task exploit/143\n rt6_fill_node.isra.0 (net/ipv6/route.c:5799)\n fib6_rt_update (net/ipv6/route.c:6412)\n __nexthop_replace_notify (net/ipv4/nexthop.c:2542)\n rtm_new_nexthop (net/ipv4/nexthop.c:2554)\n rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n\n BUG: KASAN: slab-use-after-free in fib6_check_nh_list (net/ipv4/nexthop.c:1605)\n Read of size 8 at addr ffff888014a7d068 by task exploit/142\n fib6_check_nh_list (net/ipv4/nexthop.c:1605)\n rtm_new_nexthop (net/ipv4/nexthop.c:2575)\n rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n\nBoth walks only read the entries and take no tb6_lock, so protect them\nwith nh-\u003elock; fib6_rt_update() uses gfp_any(), which returns GFP_ATOMIC\nunder the lock."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The bug is reached only via local RTNETLINK messages (RTM_NEWNEXTHOP replace and concurrent RTM_NEWROUTE/RTM_DELROUTE) sent on AF_NETLINK sockets, not by processing remote network packets.\nAC:L - An attacker can reliably trigger the race by running concurrent netlink threads that replace a nexthop while deleting IPv6 routes bound to it; both sides of the race are attacker-controlled, as demonstrated by the reported KASAN reproducers.\nPR:L - All vulnerable rtnetlink handlers require CAP_NET_ADMIN via netlink_net_capable(), which unprivileged local users can obtain inside a user/network namespace (unshare -Urn), not only real init-namespace root.\nUI:N - Exploitation requires no victim interaction beyond the attacker issuing coordinated netlink configuration commands from local processes.\nS:C - A successful UAF from CAP_NET_ADMIN inside a user/network namespace can corrupt host kernel memory and escape the container sandbox to compromise the host system.\nC:H - The race performs use-after-free reads of freed fib6_info objects (e.g., fib6_src and fib6_flags in fib6_check_nh_list and rt6_fill_node), enabling arbitrary kernel memory disclosure via heap reuse.\nI:H - Slab UAF on fib6_info during nexthop replace notification can be leveraged with heap spraying for arbitrary kernel writes and local privilege escalation to host root.\nA:H - The bug provably causes slab-use-after-free kernel oops (KASAN) during route notification and can panic or hang the system when triggered repeatedly."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:48:41.938Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/bb2b072c619c1f741a6234257050f72005dc63ef"
},
{
"url": "https://git.kernel.org/stable/c/072cd1f21819dedd2252e704d255de3b0cfc61a7"
}
],
"title": "nexthop: take nh-\u003elock for f6i_list walks in replace check and notify",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74562",
"datePublished": "2026-08-15T12:28:05.154Z",
"dateReserved": "2026-08-15T05:44:03.916Z",
"dateUpdated": "2026-08-17T05:48:41.938Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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