CVE-2025-71088
- Source
- https://cve.org/CVERecord?id=CVE-2025-71088
- Import Source
- https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-71088.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/CVE-2025-71088
- Downstream
- Related
- Published
- 2026-01-13T15:34:50.377Z
- Modified
- 2026-01-30T00:41:47.208098Z
- Summary
- mptcp: fallback earlier on simult connection
- Details
-
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 subflowdataready+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:subflowdataready+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> tcpdataqueue+0x13b0/0x4f90 net/ipv4/tcpinput.c:5197 tcprcvstateprocess+0xfdf/0x4ec0 net/ipv4/tcpinput.c:6922 tcpv6dorcv+0x492/0x1740 net/ipv6/tcpipv6.c:1672 tcpv6rcv+0x2976/0x41e0 net/ipv6/tcpipv6.c:1918 ip6protocoldeliverrcu+0x188/0x1520 net/ipv6/ip6input.c:438 ip6inputfinish+0x1e4/0x4b0 net/ipv6/ip6input.c:489 NFHOOK include/linux/netfilter.h:318 [inline] NFHOOK include/linux/netfilter.h:312 [inline] ip6input+0x105/0x2f0 net/ipv6/ip6input.c:500 dstinput include/net/dst.h:471 [inline] ip6rcvfinish net/ipv6/ip6input.c:79 [inline] NFHOOK include/linux/netfilter.h:318 [inline] NFHOOK include/linux/netfilter.h:312 [inline] ipv6rcv+0x264/0x650 net/ipv6/ip6input.c:311 _netifreceiveskbonecore+0x12d/0x1e0 net/core/dev.c:5979 _netifreceiveskb+0x1d/0x160 net/core/dev.c:6092 processbacklog+0x442/0x15e0 net/core/dev.c:6444 _napipoll.constprop.0+0xba/0x550 net/core/dev.c:7494 napipoll net/core/dev.c:7557 [inline] netrxaction+0xa9f/0xfe0 net/core/dev.c:7684 handlesoftirqs+0x216/0x8e0 kernel/softirq.c:579 runksoftirqd kernel/softirq.c:968 [inline] runksoftirqd+0x3a/0x60 kernel/softirq.c:960 smpbootthreadfn+0x3f7/0xae0 kernel/smpboot.c:160 kthread+0x3c2/0x780 kernel/kthread.c:463 retfromfork+0x5d7/0x6f0 arch/x86/kernel/process.c:148 retfromforkasm+0x1a/0x30 arch/x86/entry/entry64.S:245 </TASK>
The TCP subflow can process the simult-connect syn-ack packet after transitioning to TCPFIN1 state, bypassing the MPTCP fallback check, as the skstatechange() callback is not invoked for * -> FINWAIT1 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.
- Database specific
{ "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71088.json", "cna_assigner": "Linux" }- References
-
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- https://git.kernel.org/stable/c/25f1ae942c097b7ae4ce5c2b9c6fefb8e3672b86
- https://git.kernel.org/stable/c/71154bbe49423128c1c8577b6576de1ed6836830
- https://git.kernel.org/stable/c/79f80a7a47849ef1b3c25a0bedcc448b9cb551c1
- https://git.kernel.org/stable/c/b5f46a08269265e2f5e87d855287d6d22de0a32b
- https://git.kernel.org/stable/c/c9bf315228287653522894df9d851e9b43db9516
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71088.json
- https://nvd.nist.gov/vuln/detail/CVE-2025-71088
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced01b7822700f2256900089e00390e119e1ad545dfFixedb5f46a08269265e2f5e87d855287d6d22de0a32b
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced1e777f39b4d75e599a3aac8e0f67d739474f198cFixedc9bf315228287653522894df9d851e9b43db9516Fixed79f80a7a47849ef1b3c25a0bedcc448b9cb551c1Fixed25f1ae942c097b7ae4ce5c2b9c6fefb8e3672b86Fixed71154bbe49423128c1c8577b6576de1ed6836830