GHSA-G66H-HCWJ-F29F
Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 15:31In the Linux kernel, the following vulnerability has been resolved:
ipv6: fix fib6 walker UAF on seq stop
ipv6_route_iter_active() treats a walker in FWS_U at the table root as already unlinked. fib6_del_route() can move a still-linked walker into that same state when the current leaf is the last route at the root, so ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq private object can then be freed while it remains on net->ipv6.fib6_walkers. A later route deletion walks the dangling list and uses the freed walker.
Use the list head as membership state and reinitialize it when unlinking. Keep the existing w->node check so a never-started iterator with a zeroed private object is not treated as linked.
The same stop helper is used by /proc/net/ipv6_route and by the BPF ipv6_route iterator. The BPF show path only widens the race.
{
"affected": [],
"aliases": [
"CVE-2026-97940"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-25T11:17:21Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix fib6 walker UAF on seq stop\n\nipv6_route_iter_active() treats a walker in FWS_U at the table root as\nalready unlinked. fib6_del_route() can move a still-linked walker into\nthat same state when the current leaf is the last route at the root,\nso ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq\nprivate object can then be freed while it remains on\nnet-\u003eipv6.fib6_walkers. A later route deletion walks the dangling list\nand uses the freed walker.\n\nUse the list head as membership state and reinitialize it when\nunlinking. Keep the existing w-\u003enode check so a never-started iterator\nwith a zeroed private object is not treated as linked.\n\nThe same stop helper is used by /proc/net/ipv6_route and by the BPF\nipv6_route iterator. The BPF show path only widens the race.",
"id": "GHSA-g66h-hcwj-f29f",
"modified": "2026-09-25T15:31:44Z",
"published": "2026-09-25T12:31:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97940"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0eede1689610e9eeaf729ba86fd1321799eb91a0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/19b4ed644d68098cc62ab612727f40d30f43476c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b89b691dd00bf39b9ba39ab9446f8c62f419fa7b"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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