tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect().

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-39955
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-10-09 10:15:36 UTC
Updated2026-07-14 13:17:51 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect(). syzbot reported the splat below where a socket had tcp_sk(sk)->fastopen_rsk in the TCP_ESTABLISHED state. [0] syzbot reused the server-side TCP Fast Open socket as a new client before the TFO socket completes 3WHS: 1. accept() 2. connect(AF_UNSPEC) 3. connect() to another destination As of accept(), sk->sk_state is TCP_SYN_RECV, and tcp_disconnect() changes it to TCP_CLOSE and makes connect() possible, which restarts timers. Since tcp_disconnect() forgot to clear tcp_sk(sk)->fastopen_rsk, the retransmit timer triggered the warning and the intended packet was not retransmitted. Let's call reqsk_fastopen_remove() in tcp_disconnect(). [0]: WARNING: CPU: 2 PID: 0 at net/ipv4/tcp_timer.c:542 tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7)) Modules linked in: CPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.17.0-rc5-g201825fb4278 #62 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7)) Code: 41 55 41 54 55 53 48 8b af b8 08 00 00 48 89 fb 48 85 ed 0f 84 55 01 00 00 0f b6 47 12 3c 03 74 0c 0f b6 47 12 3c 04 74 04 90 <0f> 0b 90 48 8b 85 c0 00 00 00 48 89 ef 48 8b 40 30 e8 6a 4f 06 3e RSP: 0018:ffffc900002f8d40 EFLAGS: 00010293 RAX: 0000000000000002 RBX: ffff888106911400 RCX: 0000000000000017 RDX: 0000000002517619 RSI: ffffffff83764080 RDI: ffff888106911400 RBP: ffff888106d5c000 R08: 0000000000000001 R09: ffffc900002f8de8 R10: 00000000000000c2 R11: ffffc900002f8ff8 R12: ffff888106911540 R13: ffff888106911480 R14: ffff888106911840 R15: ffffc900002f8de0 FS: 0000000000000000(0000) GS:ffff88907b768000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8044d69d90 CR3: 0000000002c30003 CR4: 0000000000370ef0 Call Trace: <IRQ> tcp_write_timer (net/ipv4/tcp_timer.c:738) call_timer_fn (kernel/time/timer.c:1747) __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2372) timer_expire_remote (kernel/time/timer.c:2385 kernel/time/timer.c:2376 kernel/time/timer.c:2135) tmigr_handle_remote_up (kernel/time/timer_migration.c:944 kernel/time/timer_migration.c:1035) __walk_groups.isra.0 (kernel/time/timer_migration.c:533 (discriminator 1)) tmigr_handle_remote (kernel/time/timer_migration.c:1096) handle_softirqs (./arch/x86/include/asm/jump_label.h:36 ./include/trace/events/irq.h:142 kernel/softirq.c:580) irq_exit_rcu (kernel/softirq.c:614 kernel/softirq.c:453 kernel/softirq.c:680 kernel/softirq.c:696) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1050 (discriminator 35) arch/x86/kernel/apic/apic.c:1050 (discriminator 35)) </IRQ>

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: NVD-CWE-noinfo

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 7ec092a91ff351dcde89c23e795b73a328274db6 git Not specified
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 a4378dedd6e07e62f2fccb17d78c9665718763d0 git Not specified
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 33a4fdf0b4a25f8ce65380c3b0136b407ca57609 git Not specified
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 17d699727577814198d744d6afe54735c6b54c99 git Not specified
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 dfd06131107e7b699ef1e2a24ed2f7d17c917753 git Not specified
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 fa4749c065644af4db496b338452a69a3e5147d9 git Not specified
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 ae313d14b45eca7a6bb29cb9bf396d977e7d28fb git Not specified
CNA Linux Linux affected 8336886f786fdacbc19b719c1f7ea91eb70706d4 45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01 git Not specified
CNA Linux Linux affected 3.7 Not specified
CNA Linux Linux unaffected 3.7 semver Not specified
CNA Linux Linux unaffected 5.4.300 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.245 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.194 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.154 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.108 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.49 6.12.* semver Not specified
CNA Linux Linux unaffected 6.16.9 6.16.* semver Not specified
CNA Linux Linux unaffected 6.17 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/dfd06131107e7b699ef1e2a24ed2f7d17c917753 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/33a4fdf0b4a25f8ce65380c3b0136b407ca57609 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/17d699727577814198d744d6afe54735c6b54c99 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/ae313d14b45eca7a6bb29cb9bf396d977e7d28fb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/7ec092a91ff351dcde89c23e795b73a328274db6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/a4378dedd6e07e62f2fccb17d78c9665718763d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/fa4749c065644af4db496b338452a69a3e5147d9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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