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vuln-cve/data/2026/98xxx/CVE-2026-98276.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-98276",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-09-25T10:25:14.334Z",
"datePublished": "2026-10-06T08:45:36.837Z",
"dateUpdated": "2026-10-19T09:16:47.879Z"
},
"containers": {
"cna": {
"providerMetadata": {
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux",
"dateUpdated": "2026-10-19T09:16:47.879Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lock the socket in sock_gettstamp()\n\nsk->sk_flags must only be changed while holding the socket lock,\nbecause sock_set_flag() and sock_reset_flag() use non atomic\noperations (__set_bit() and __clear_bit()).\n\nsock_gettstamp() is one of the last places where a bit of sk->sk_flags\nis changed from a syscall without owning the socket lock, through\nsock_enable_timestamp(sk, SOCK_TIMESTAMP).\n\nsk_set_memalloc() and sk_clear_memalloc() also change sk->sk_flags\nwithout the socket lock, but their callers (nbd, iscsi_tcp, nvme-tcp,\nsunrpc, wireguard) need a careful audit, this will be addressed in a\nseparate patch.\n\nJungwoo Lee and Wongi Lee reported an UDP socket use-after-free\ncaused by this bug: a SIOCGSTAMPNS_NEW ioctl racing with bind()\ncan cancel the SOCK_RCU_FREE bit that udp_lib_get_port() just set,\nbecause both threads perform a read-modify-write on the same word.\n\n CPU 0 (bind) CPU 1 (SIOCGSTAMPNS_NEW)\n -------------------------------- ----------------------------\n read sk_flags = F read sk_flags = F\n compute F | BIT(SOCK_RCU_FREE) compute F | BIT(SOCK_TIMESTAMP)\n store F | BIT(SOCK_RCU_FREE)\n sk_add_node_rcu(sk, ...)\n store F | BIT(SOCK_TIMESTAMP)\n\nAfter the lost update, SOCK_RCU_FREE is clear while the socket is\nvisible to lockless UDP receive lookups. sk_destruct() then frees\nthe socket immediately instead of waiting for a RCU grace period,\nwhile the receive path still holds a reference-less pointer to it:\n\n BUG: KASAN: slab-use-after-free in ipv4_pktinfo_prepare+0x30/0x410\n Read of size 8 at addr ffff888008806610 by task exploit/207\n CPU: 0 UID: 1000 PID: 207 Comm: exploit Not tainted 6.12.95+ #1\n ipv4_pktinfo_prepare+0x30/0x410\n udp_queue_rcv_one_skb+0x51c/0x1180\n udp_unicast_rcv_skb+0x109/0x350\n ip_protocol_deliver_rcu+0x14b/0x310\n ip_local_deliver_finish+0x29d/0x390\n ip_local_deliver+0x24d/0x2a0\n\nOnly grab the socket lock when SOCK_TIMESTAMP has to be set,\nto keep the common case lockless."
}
],
"metrics": [
{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 7.8,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The lost update is caused by a local process racing the SIOCGSTAMP*/SIOCGSTAMPNS* ioctl (sock_ioctl -> sock_gettstamp -> sock_enable_timestamp) against bind() -> udp_lib_get_port() setting SOCK_RCU_FREE on its own UDP socket. No network message supplies the triggering state; remote packets only deliver into the already-corrupted socket.\nAC:L - The attacker owns both sides of the race: one thread calls bind(), another calls the timestamp ioctl on the same fd. It can create, bind and close sockets in a loop until the __set_bit read-modify-write on sk_flags loses SOCK_RCU_FREE, then send loopback UDP to hit the freed sock.\nPR:L - It only needs an ordinary AF_INET/AF_INET6 UDP socket. sock_ioctl's SIOCGSTAMP case and inet bind to an ephemeral or unprivileged port have no capability check, and the reporters reproduced it as UID 1000.\nUI:N - The attacker drives every step (socket creation, concurrent bind/ioctl, close, sending packets to its own port) with no action from any other user.\nS:U - The freed struct sock and the code that reads it are both in the same kernel; this is local kernel memory corruption that leads to privilege escalation inside one authority, with no VM or sandbox boundary crossed.\nC:H - With SOCK_RCU_FREE lost, sk_destruct frees the UDP struct sock immediately while lockless RCU lookups in udp_unicast_rcv_skb/udp_queue_rcv_one_skb still hold a pointer to it. A slab UAF of a struct sock can be reclaimed with sprayed data to leak kernel memory.\nI:H - The receive path operates on the freed sock: it queues skbs, updates counters and reads sk_prot/sk_filter-related fields. If the attacker reclaims the slab, these become writes into, and function-pointer use from, attacker-controlled memory, which is a path to control-flow hijack.\nA:H - Even when not exploited, the use-after-free in ipv4_pktinfo_prepare/udp_queue_rcv_one_skb (shown by KASAN) corrupts slab memory and can oops or panic the kernel."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/core/sock.c"
],
"versions": [
{
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"lessThan": "18899e2e4023369a8f7739c2255a59a9748d8d17",
"status": "affected",
"versionType": "git"
},
{
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"lessThan": "88c804847dd87dc613b771b392ccecdb94725032",
"status": "affected",
"versionType": "git"
},
{
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"lessThan": "3b12d3967e96f1b7b977d9fc352ae29a1b299a82",
"status": "affected",
"versionType": "git"
},
{
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"lessThan": "17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f",
"status": "affected",
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},
{
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"status": "affected",
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"status": "affected",
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},
{
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"lessThan": "899650bbf985b7bfd2a7b808357df9b16e6d6959",
"status": "affected",
"versionType": "git"
},
{
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"lessThan": "9ed55f3dbef4f4adfe65eb03b0c35c53229a8490",
"status": "affected",
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}
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},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"net/core/sock.c"
],
"versions": [
{
"version": "2.6.12",
"status": "affected"
},
{
"version": "0",
"lessThan": "2.6.12",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.10.271",
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "5.15.222",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.1.189",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.6.158",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.12.112",
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "6.18.54",
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.2.8",
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.12",
"versionEndExcluding": "5.10.271"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.12",
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.12",
"versionEndExcluding": "7.2.8"
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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "2.6.12",
"versionEndExcluding": "7.3"
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],
"references": [
{
"url": "https://git.kernel.org/stable/c/18899e2e4023369a8f7739c2255a59a9748d8d17"
},
{
"url": "https://git.kernel.org/stable/c/88c804847dd87dc613b771b392ccecdb94725032"
},
{
"url": "https://git.kernel.org/stable/c/3b12d3967e96f1b7b977d9fc352ae29a1b299a82"
},
{
"url": "https://git.kernel.org/stable/c/17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f"
},
{
"url": "https://git.kernel.org/stable/c/1f73253add8365d0dad0a4f421acaa8c21d20cef"
},
{
"url": "https://git.kernel.org/stable/c/d9f96bc2d822501f84d1caa6275a2c6b316ca2c4"
},
{
"url": "https://git.kernel.org/stable/c/899650bbf985b7bfd2a7b808357df9b16e6d6959"
},
{
"url": "https://git.kernel.org/stable/c/9ed55f3dbef4f4adfe65eb03b0c35c53229a8490"
}
],
"title": "net: lock the socket in sock_gettstamp()",
"x_generator": {
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}
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}
}