CVE-2026-98374
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: tcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack() When tcp_send_synack() replaces the cloned SYN skb at the head of the retransmit queue with a copy, it frees the original with tcp_rtx_queue_unlink_and_free() and only repairs tp->highest_sack. tp->retransmit_skb_hint keeps pointing at the freed skbuff_fclone_cache object. The dangling hint is read in tcp_verify_retransmit_hint() and used as the root of the rbtree walk in tcp_xmit_retransmit_queue(). An unprivileged TFO client (sendmsg(MSG_FASTOPEN)) can arm the hint with an attacker-supplied ICMP fragmentation-needed message, after which a simultaneous open frees the armed SYN skb: BUG: KASAN: slab-use-after-free in tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316) Read of size 4 at addr ffff88800604d928 by task swapper/1/0 Call Trace: tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316) tcp_simple_retransmit (net/ipv4/tcp_input.c:3158) tcp_v4_err (net/ipv4/tcp_ipv4.c:587) Sync the hint to the copy.
Severity
HIGH
CVSS score
8.8
(v3.1)
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-10-07 13:17:23.023000
Last modified
2026-10-24 14:16:39.560000
View original CVE JSON
{
"id": "CVE-2026-98374",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-07T13:17:23.023",
"lastModified": "2026-10-24T14:16:39.560",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()\n\nWhen tcp_send_synack() replaces the cloned SYN skb at the head of the\nretransmit queue with a copy, it frees the original with\ntcp_rtx_queue_unlink_and_free() and only repairs tp->highest_sack.\ntp->retransmit_skb_hint keeps pointing at the freed\nskbuff_fclone_cache object.\n\nThe dangling hint is read in tcp_verify_retransmit_hint() and used as\nthe root of the rbtree walk in tcp_xmit_retransmit_queue(). An\nunprivileged TFO client (sendmsg(MSG_FASTOPEN)) can arm the hint with\nan attacker-supplied ICMP fragmentation-needed message, after which a\nsimultaneous open frees the armed SYN skb:\n\n BUG: KASAN: slab-use-after-free in tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316)\n Read of size 4 at addr ffff88800604d928 by task swapper/1/0\n Call Trace:\n tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316)\n tcp_simple_retransmit (net/ipv4/tcp_input.c:3158)\n tcp_v4_err (net/ipv4/tcp_ipv4.c:587)\n\nSync the hint to the copy."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/ipv4/tcp_output.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
"lessThan": "fad6d429651e748365e93ca54645accc212f0018",
"versionType": "git",
"status": "affected"
},
{
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{
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{
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}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/ipv4/tcp_output.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "5.11",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.11",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.222",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.189",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.158",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.112",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.55",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.9",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "REQUIRED",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 2.8,
"impactScore": 5.9
}
]
},
"references": [
{
"url": "https://git.kernel.org/stable/c/0f87720c7e4bcab07c24888b3cf12bfe857bb90e",
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{
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{
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{
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{
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}