GHSA-M7W2-JXF2-6J36
Vulnerability from github – Published: 2026-04-24 15:32 – Updated: 2026-07-14 15:31In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_ct: fix use-after-free in timeout object destroy
nft_ct_timeout_obj_destroy() frees the timeout object with kfree() immediately after nf_ct_untimeout(), without waiting for an RCU grace period. Concurrent packet processing on other CPUs may still hold RCU-protected references to the timeout object obtained via rcu_dereference() in nf_ct_timeout_data().
Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer freeing until after an RCU grace period, matching the approach already used in nfnetlink_cttimeout.c.
KASAN report: BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0 Read of size 4 at addr ffff8881035fe19c by task exploit/80
Call Trace: nf_conntrack_tcp_packet+0x1381/0x29d0 nf_conntrack_in+0x612/0x8b0 nf_hook_slow+0x70/0x100 __ip_local_out+0x1b2/0x210 tcp_sendmsg_locked+0x722/0x1580 __sys_sendto+0x2d8/0x320
Allocated by task 75: nft_ct_timeout_obj_init+0xf6/0x290 nft_obj_init+0x107/0x1b0 nf_tables_newobj+0x680/0x9c0 nfnetlink_rcv_batch+0xc29/0xe00
Freed by task 26: nft_obj_destroy+0x3f/0xa0 nf_tables_trans_destroy_work+0x51c/0x5c0 process_one_work+0x2c4/0x5a0
{
"affected": [],
"aliases": [
"CVE-2026-31665"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-24T15:16:46Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_ct: fix use-after-free in timeout object destroy\n\nnft_ct_timeout_obj_destroy() frees the timeout object with kfree()\nimmediately after nf_ct_untimeout(), without waiting for an RCU grace\nperiod. Concurrent packet processing on other CPUs may still hold\nRCU-protected references to the timeout object obtained via\nrcu_dereference() in nf_ct_timeout_data().\n\nAdd an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer\nfreeing until after an RCU grace period, matching the approach already\nused in nfnetlink_cttimeout.c.\n\nKASAN report:\n BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0\n Read of size 4 at addr ffff8881035fe19c by task exploit/80\n\n Call Trace:\n nf_conntrack_tcp_packet+0x1381/0x29d0\n nf_conntrack_in+0x612/0x8b0\n nf_hook_slow+0x70/0x100\n __ip_local_out+0x1b2/0x210\n tcp_sendmsg_locked+0x722/0x1580\n __sys_sendto+0x2d8/0x320\n\n Allocated by task 75:\n nft_ct_timeout_obj_init+0xf6/0x290\n nft_obj_init+0x107/0x1b0\n nf_tables_newobj+0x680/0x9c0\n nfnetlink_rcv_batch+0xc29/0xe00\n\n Freed by task 26:\n nft_obj_destroy+0x3f/0xa0\n nf_tables_trans_destroy_work+0x51c/0x5c0\n process_one_work+0x2c4/0x5a0",
"id": "GHSA-m7w2-jxf2-6j36",
"modified": "2026-07-14T15:31:54Z",
"published": "2026-04-24T15:32:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31665"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/070abdf1b04325b21a20a2a0c39a2208af107275"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b42aca3660dc2627a29a38131597ca610dc451f9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c458fc1c278a65ad5381083121d39a479973ebed"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c581e5c8f2b59158f62efe61c1a3dc36189081ff"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d0983b48c10d1509fd795c155f8b1e832e1369ff"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f16fe84879a5280f05ebbcea593a189ba0f3e79a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f8dca15a1b190787bbd03285304b569631160eda"
}
],
"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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