CVE-2025-71088 (GCVE-0-2025-71088)
Vulnerability from cvelistv5 – Published: 2026-01-13 15:34 – Updated: 2026-01-13 15:34
VLAI?
Title
mptcp: fallback earlier on simult connection
Summary
In the Linux kernel, the following vulnerability has been resolved:
mptcp: fallback earlier on simult connection
Syzkaller reports a simult-connect race leading to inconsistent fallback
status:
WARNING: CPU: 3 PID: 33 at net/mptcp/subflow.c:1515 subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515
Modules linked in:
CPU: 3 UID: 0 PID: 33 Comm: ksoftirqd/3 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515
Code: 89 ee e8 78 61 3c f6 40 84 ed 75 21 e8 8e 66 3c f6 44 89 fe bf 07 00 00 00 e8 c1 61 3c f6 41 83 ff 07 74 09 e8 76 66 3c f6 90 <0f> 0b 90 e8 6d 66 3c f6 48 89 df e8 e5 ad ff ff 31 ff 89 c5 89 c6
RSP: 0018:ffffc900006cf338 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888031acd100 RCX: ffffffff8b7f2abf
RDX: ffff88801e6ea440 RSI: ffffffff8b7f2aca RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000007
R10: 0000000000000004 R11: 0000000000002c10 R12: ffff88802ba69900
R13: 1ffff920000d9e67 R14: ffff888046f81800 R15: 0000000000000004
FS: 0000000000000000(0000) GS:ffff8880d69bc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560fc0ca1670 CR3: 0000000032c3a000 CR4: 0000000000352ef0
Call Trace:
<TASK>
tcp_data_queue+0x13b0/0x4f90 net/ipv4/tcp_input.c:5197
tcp_rcv_state_process+0xfdf/0x4ec0 net/ipv4/tcp_input.c:6922
tcp_v6_do_rcv+0x492/0x1740 net/ipv6/tcp_ipv6.c:1672
tcp_v6_rcv+0x2976/0x41e0 net/ipv6/tcp_ipv6.c:1918
ip6_protocol_deliver_rcu+0x188/0x1520 net/ipv6/ip6_input.c:438
ip6_input_finish+0x1e4/0x4b0 net/ipv6/ip6_input.c:489
NF_HOOK include/linux/netfilter.h:318 [inline]
NF_HOOK include/linux/netfilter.h:312 [inline]
ip6_input+0x105/0x2f0 net/ipv6/ip6_input.c:500
dst_input include/net/dst.h:471 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
NF_HOOK include/linux/netfilter.h:318 [inline]
NF_HOOK include/linux/netfilter.h:312 [inline]
ipv6_rcv+0x264/0x650 net/ipv6/ip6_input.c:311
__netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5979
__netif_receive_skb+0x1d/0x160 net/core/dev.c:6092
process_backlog+0x442/0x15e0 net/core/dev.c:6444
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7494
napi_poll net/core/dev.c:7557 [inline]
net_rx_action+0xa9f/0xfe0 net/core/dev.c:7684
handle_softirqs+0x216/0x8e0 kernel/softirq.c:579
run_ksoftirqd kernel/softirq.c:968 [inline]
run_ksoftirqd+0x3a/0x60 kernel/softirq.c:960
smpboot_thread_fn+0x3f7/0xae0 kernel/smpboot.c:160
kthread+0x3c2/0x780 kernel/kthread.c:463
ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
The TCP subflow can process the simult-connect syn-ack packet after
transitioning to TCP_FIN1 state, bypassing the MPTCP fallback check,
as the sk_state_change() callback is not invoked for * -> FIN_WAIT1
transitions.
That will move the msk socket to an inconsistent status and the next
incoming data will hit the reported splat.
Close the race moving the simult-fallback check at the earliest possible
stage - that is at syn-ack generation time.
About the fixes tags: [2] was supposed to also fix this issue introduced
by [3]. [1] is required as a dependence: it was not explicitly marked as
a fix, but it is one and it has already been backported before [3]. In
other words, this commit should be backported up to [3], including [2]
and [1] if that's not already there.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Affected:
01b7822700f2256900089e00390e119e1ad545df , < b5f46a08269265e2f5e87d855287d6d22de0a32b
(git)
Affected: 1e777f39b4d75e599a3aac8e0f67d739474f198c , < c9bf315228287653522894df9d851e9b43db9516 (git) Affected: 1e777f39b4d75e599a3aac8e0f67d739474f198c , < 79f80a7a47849ef1b3c25a0bedcc448b9cb551c1 (git) Affected: 1e777f39b4d75e599a3aac8e0f67d739474f198c , < 25f1ae942c097b7ae4ce5c2b9c6fefb8e3672b86 (git) Affected: 1e777f39b4d75e599a3aac8e0f67d739474f198c , < 71154bbe49423128c1c8577b6576de1ed6836830 (git) |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/mptcp/options.c",
"net/mptcp/protocol.h",
"net/mptcp/subflow.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "b5f46a08269265e2f5e87d855287d6d22de0a32b",
"status": "affected",
"version": "01b7822700f2256900089e00390e119e1ad545df",
"versionType": "git"
},
{
"lessThan": "c9bf315228287653522894df9d851e9b43db9516",
"status": "affected",
"version": "1e777f39b4d75e599a3aac8e0f67d739474f198c",
"versionType": "git"
},
{
"lessThan": "79f80a7a47849ef1b3c25a0bedcc448b9cb551c1",
"status": "affected",
"version": "1e777f39b4d75e599a3aac8e0f67d739474f198c",
"versionType": "git"
},
{
"lessThan": "25f1ae942c097b7ae4ce5c2b9c6fefb8e3672b86",
"status": "affected",
"version": "1e777f39b4d75e599a3aac8e0f67d739474f198c",
"versionType": "git"
},
{
"lessThan": "71154bbe49423128c1c8577b6576de1ed6836830",
"status": "affected",
"version": "1e777f39b4d75e599a3aac8e0f67d739474f198c",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/mptcp/options.c",
"net/mptcp/protocol.h",
"net/mptcp/subflow.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.2"
},
{
"lessThan": "6.2",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.160",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.120",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.65",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.19-rc4",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.160",
"versionStartIncluding": "6.1.110",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.120",
"versionStartIncluding": "6.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.65",
"versionStartIncluding": "6.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.4",
"versionStartIncluding": "6.2",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.19-rc4",
"versionStartIncluding": "6.2",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: fallback earlier on simult connection\n\nSyzkaller reports a simult-connect race leading to inconsistent fallback\nstatus:\n\n WARNING: CPU: 3 PID: 33 at net/mptcp/subflow.c:1515 subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515\n Modules linked in:\n CPU: 3 UID: 0 PID: 33 Comm: ksoftirqd/3 Not tainted syzkaller #0 PREEMPT(full)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\n RIP: 0010:subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515\n Code: 89 ee e8 78 61 3c f6 40 84 ed 75 21 e8 8e 66 3c f6 44 89 fe bf 07 00 00 00 e8 c1 61 3c f6 41 83 ff 07 74 09 e8 76 66 3c f6 90 \u003c0f\u003e 0b 90 e8 6d 66 3c f6 48 89 df e8 e5 ad ff ff 31 ff 89 c5 89 c6\n RSP: 0018:ffffc900006cf338 EFLAGS: 00010246\n RAX: 0000000000000000 RBX: ffff888031acd100 RCX: ffffffff8b7f2abf\n RDX: ffff88801e6ea440 RSI: ffffffff8b7f2aca RDI: 0000000000000005\n RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000007\n R10: 0000000000000004 R11: 0000000000002c10 R12: ffff88802ba69900\n R13: 1ffff920000d9e67 R14: ffff888046f81800 R15: 0000000000000004\n FS: 0000000000000000(0000) GS:ffff8880d69bc000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 0000560fc0ca1670 CR3: 0000000032c3a000 CR4: 0000000000352ef0\n Call Trace:\n \u003cTASK\u003e\n tcp_data_queue+0x13b0/0x4f90 net/ipv4/tcp_input.c:5197\n tcp_rcv_state_process+0xfdf/0x4ec0 net/ipv4/tcp_input.c:6922\n tcp_v6_do_rcv+0x492/0x1740 net/ipv6/tcp_ipv6.c:1672\n tcp_v6_rcv+0x2976/0x41e0 net/ipv6/tcp_ipv6.c:1918\n ip6_protocol_deliver_rcu+0x188/0x1520 net/ipv6/ip6_input.c:438\n ip6_input_finish+0x1e4/0x4b0 net/ipv6/ip6_input.c:489\n NF_HOOK include/linux/netfilter.h:318 [inline]\n NF_HOOK include/linux/netfilter.h:312 [inline]\n ip6_input+0x105/0x2f0 net/ipv6/ip6_input.c:500\n dst_input include/net/dst.h:471 [inline]\n ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]\n NF_HOOK include/linux/netfilter.h:318 [inline]\n NF_HOOK include/linux/netfilter.h:312 [inline]\n ipv6_rcv+0x264/0x650 net/ipv6/ip6_input.c:311\n __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5979\n __netif_receive_skb+0x1d/0x160 net/core/dev.c:6092\n process_backlog+0x442/0x15e0 net/core/dev.c:6444\n __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7494\n napi_poll net/core/dev.c:7557 [inline]\n net_rx_action+0xa9f/0xfe0 net/core/dev.c:7684\n handle_softirqs+0x216/0x8e0 kernel/softirq.c:579\n run_ksoftirqd kernel/softirq.c:968 [inline]\n run_ksoftirqd+0x3a/0x60 kernel/softirq.c:960\n smpboot_thread_fn+0x3f7/0xae0 kernel/smpboot.c:160\n kthread+0x3c2/0x780 kernel/kthread.c:463\n ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n \u003c/TASK\u003e\n\nThe TCP subflow can process the simult-connect syn-ack packet after\ntransitioning to TCP_FIN1 state, bypassing the MPTCP fallback check,\nas the sk_state_change() callback is not invoked for * -\u003e FIN_WAIT1\ntransitions.\n\nThat will move the msk socket to an inconsistent status and the next\nincoming data will hit the reported splat.\n\nClose the race moving the simult-fallback check at the earliest possible\nstage - that is at syn-ack generation time.\n\nAbout the fixes tags: [2] was supposed to also fix this issue introduced\nby [3]. [1] is required as a dependence: it was not explicitly marked as\na fix, but it is one and it has already been backported before [3]. In\nother words, this commit should be backported up to [3], including [2]\nand [1] if that\u0027s not already there."
}
],
"providerMetadata": {
"dateUpdated": "2026-01-13T15:34:50.377Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/b5f46a08269265e2f5e87d855287d6d22de0a32b"
},
{
"url": "https://git.kernel.org/stable/c/c9bf315228287653522894df9d851e9b43db9516"
},
{
"url": "https://git.kernel.org/stable/c/79f80a7a47849ef1b3c25a0bedcc448b9cb551c1"
},
{
"url": "https://git.kernel.org/stable/c/25f1ae942c097b7ae4ce5c2b9c6fefb8e3672b86"
},
{
"url": "https://git.kernel.org/stable/c/71154bbe49423128c1c8577b6576de1ed6836830"
}
],
"title": "mptcp: fallback earlier on simult connection",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-71088",
"datePublished": "2026-01-13T15:34:50.377Z",
"dateReserved": "2026-01-13T15:30:19.649Z",
"dateUpdated": "2026-01-13T15:34:50.377Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2025-71088\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-01-13T16:16:08.460\",\"lastModified\":\"2026-01-13T16:16:08.460\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmptcp: fallback earlier on simult connection\\n\\nSyzkaller reports a simult-connect race leading to inconsistent fallback\\nstatus:\\n\\n WARNING: CPU: 3 PID: 33 at net/mptcp/subflow.c:1515 subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515\\n Modules linked in:\\n CPU: 3 UID: 0 PID: 33 Comm: ksoftirqd/3 Not tainted syzkaller #0 PREEMPT(full)\\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\\n RIP: 0010:subflow_data_ready+0x40b/0x7c0 net/mptcp/subflow.c:1515\\n Code: 89 ee e8 78 61 3c f6 40 84 ed 75 21 e8 8e 66 3c f6 44 89 fe bf 07 00 00 00 e8 c1 61 3c f6 41 83 ff 07 74 09 e8 76 66 3c f6 90 \u003c0f\u003e 0b 90 e8 6d 66 3c f6 48 89 df e8 e5 ad ff ff 31 ff 89 c5 89 c6\\n RSP: 0018:ffffc900006cf338 EFLAGS: 00010246\\n RAX: 0000000000000000 RBX: ffff888031acd100 RCX: ffffffff8b7f2abf\\n RDX: ffff88801e6ea440 RSI: ffffffff8b7f2aca RDI: 0000000000000005\\n RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000007\\n R10: 0000000000000004 R11: 0000000000002c10 R12: ffff88802ba69900\\n R13: 1ffff920000d9e67 R14: ffff888046f81800 R15: 0000000000000004\\n FS: 0000000000000000(0000) GS:ffff8880d69bc000(0000) knlGS:0000000000000000\\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\\n CR2: 0000560fc0ca1670 CR3: 0000000032c3a000 CR4: 0000000000352ef0\\n Call Trace:\\n \u003cTASK\u003e\\n tcp_data_queue+0x13b0/0x4f90 net/ipv4/tcp_input.c:5197\\n tcp_rcv_state_process+0xfdf/0x4ec0 net/ipv4/tcp_input.c:6922\\n tcp_v6_do_rcv+0x492/0x1740 net/ipv6/tcp_ipv6.c:1672\\n tcp_v6_rcv+0x2976/0x41e0 net/ipv6/tcp_ipv6.c:1918\\n ip6_protocol_deliver_rcu+0x188/0x1520 net/ipv6/ip6_input.c:438\\n ip6_input_finish+0x1e4/0x4b0 net/ipv6/ip6_input.c:489\\n NF_HOOK include/linux/netfilter.h:318 [inline]\\n NF_HOOK include/linux/netfilter.h:312 [inline]\\n ip6_input+0x105/0x2f0 net/ipv6/ip6_input.c:500\\n dst_input include/net/dst.h:471 [inline]\\n ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]\\n NF_HOOK include/linux/netfilter.h:318 [inline]\\n NF_HOOK include/linux/netfilter.h:312 [inline]\\n ipv6_rcv+0x264/0x650 net/ipv6/ip6_input.c:311\\n __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5979\\n __netif_receive_skb+0x1d/0x160 net/core/dev.c:6092\\n process_backlog+0x442/0x15e0 net/core/dev.c:6444\\n __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7494\\n napi_poll net/core/dev.c:7557 [inline]\\n net_rx_action+0xa9f/0xfe0 net/core/dev.c:7684\\n handle_softirqs+0x216/0x8e0 kernel/softirq.c:579\\n run_ksoftirqd kernel/softirq.c:968 [inline]\\n run_ksoftirqd+0x3a/0x60 kernel/softirq.c:960\\n smpboot_thread_fn+0x3f7/0xae0 kernel/smpboot.c:160\\n kthread+0x3c2/0x780 kernel/kthread.c:463\\n ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148\\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\\n \u003c/TASK\u003e\\n\\nThe TCP subflow can process the simult-connect syn-ack packet after\\ntransitioning to TCP_FIN1 state, bypassing the MPTCP fallback check,\\nas the sk_state_change() callback is not invoked for * -\u003e FIN_WAIT1\\ntransitions.\\n\\nThat will move the msk socket to an inconsistent status and the next\\nincoming data will hit the reported splat.\\n\\nClose the race moving the simult-fallback check at the earliest possible\\nstage - that is at syn-ack generation time.\\n\\nAbout the fixes tags: [2] was supposed to also fix this issue introduced\\nby [3]. [1] is required as a dependence: it was not explicitly marked as\\na fix, but it is one and it has already been backported before [3]. In\\nother words, this commit should be backported up to [3], including [2]\\nand [1] if that\u0027s not already there.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/25f1ae942c097b7ae4ce5c2b9c6fefb8e3672b86\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/71154bbe49423128c1c8577b6576de1ed6836830\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/79f80a7a47849ef1b3c25a0bedcc448b9cb551c1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b5f46a08269265e2f5e87d855287d6d22de0a32b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c9bf315228287653522894df9d851e9b43db9516\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
Loading…