CVE-2025-38491 (GCVE-0-2025-38491)

Vulnerability from cvelistv5 – Published: 2025-07-28 11:21 – Updated: 2026-08-05 12:02
VLAI
Title
mptcp: make fallback action and fallback decision atomic
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: make fallback action and fallback decision atomic Syzkaller reported the following splat: WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_established net/mptcp/options.c:982 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Modules linked in: CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324dba #20 PREEMPT(voluntary) Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline] RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 <0f> 0b 90 e9 b8 f4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00 RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45 RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001 RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000 FS: 00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0 Call Trace: <IRQ> tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432 tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975 tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166 tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925 tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363 ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:469 [inline] ip_rcv_finish net/ipv4/ip_input.c:447 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088 process_backlog+0x301/0x1360 net/core/dev.c:6440 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453 napi_poll net/core/dev.c:7517 [inline] net_rx_action+0xb44/0x1010 net/core/dev.c:7644 handle_softirqs+0x1d0/0x770 kernel/softirq.c:579 do_softirq+0x3f/0x90 kernel/softirq.c:480 </IRQ> <TASK> __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524 mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985 mptcp_check_listen_stop net/mptcp/mib.h:118 [inline] __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000 mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066 inet_release+0xed/0x200 net/ipv4/af_inet.c:435 inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487 __sock_release+0xb3/0x270 net/socket.c:649 sock_close+0x1c/0x30 net/socket.c:1439 __fput+0x402/0xb70 fs/file_table.c:465 task_work_run+0x150/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xd4 ---truncated---
Severity
8.2 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 0530020a7c8f2204e784f0dbdc882bbd961fdbde , < 5586518bec27666c747cd52aabb62d485686d0bf (git)
Affected: 0530020a7c8f2204e784f0dbdc882bbd961fdbde , < 75a4c9ab8a7af0d76b31ccd1188ed178c38b35d2 (git)
Affected: 0530020a7c8f2204e784f0dbdc882bbd961fdbde , < 54999dea879fecb761225e28f274b40662918c30 (git)
Affected: 0530020a7c8f2204e784f0dbdc882bbd961fdbde , < 1d82a8fe6ee4afdc92f4e8808c9dad2a6095bbc5 (git)
Affected: 0530020a7c8f2204e784f0dbdc882bbd961fdbde , < f8a1d9b18c5efc76784f5a326e905f641f839894 (git)
Affected: 609937aa962a62e93acfc04dd370b665e6152dfb (git)
Affected: 6654efe264b014d8ea9fc38f79efb568b1b79069 (git)
Affected: 5.10.228 , < 5.11 (semver)
Affected: 5.15.169 , < 5.16 (semver)
Create a notification for this product.
Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.1.149 , ≤ 6.1.* (semver)
Unaffected: 6.6.101 , ≤ 6.6.* (semver)
Unaffected: 6.12.40 , ≤ 6.12.* (semver)
Unaffected: 6.15.8 , ≤ 6.15.* (semver)
Unaffected: 6.16 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Siemens SIMATIC CN 4100 Affected: 0 , < V5.0 (custom)
Create a notification for this product.
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: make fallback action and fallback decision atomic\n\nSyzkaller reported the following splat:\n\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback net/mptcp/protocol.h:1223 [inline]\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback net/mptcp/protocol.h:1244 [inline]\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_established net/mptcp/options.c:982 [inline]\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153\n  Modules linked in:\n  CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324dba #20 PREEMPT(voluntary)\n  Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n  RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline]\n  RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline]\n  RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline]\n  RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153\n  Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 \u003c0f\u003e 0b 90 e9 b8 f4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00\n  RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246\n  RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45\n  RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001\n  RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000\n  R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000\n  R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000\n  FS:  00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0\n  Call Trace:\n   \u003cIRQ\u003e\n   tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432\n   tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975\n   tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166\n   tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925\n   tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363\n   ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205\n   ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233\n   NF_HOOK include/linux/netfilter.h:317 [inline]\n   NF_HOOK include/linux/netfilter.h:311 [inline]\n   ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254\n   dst_input include/net/dst.h:469 [inline]\n   ip_rcv_finish net/ipv4/ip_input.c:447 [inline]\n   NF_HOOK include/linux/netfilter.h:317 [inline]\n   NF_HOOK include/linux/netfilter.h:311 [inline]\n   ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567\n   __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975\n   __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088\n   process_backlog+0x301/0x1360 net/core/dev.c:6440\n   __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453\n   napi_poll net/core/dev.c:7517 [inline]\n   net_rx_action+0xb44/0x1010 net/core/dev.c:7644\n   handle_softirqs+0x1d0/0x770 kernel/softirq.c:579\n   do_softirq+0x3f/0x90 kernel/softirq.c:480\n   \u003c/IRQ\u003e\n   \u003cTASK\u003e\n   __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407\n   local_bh_enable include/linux/bottom_half.h:33 [inline]\n   inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524\n   mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985\n   mptcp_check_listen_stop net/mptcp/mib.h:118 [inline]\n   __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000\n   mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066\n   inet_release+0xed/0x200 net/ipv4/af_inet.c:435\n   inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487\n   __sock_release+0xb3/0x270 net/socket.c:649\n   sock_close+0x1c/0x30 net/socket.c:1439\n   __fput+0x402/0xb70 fs/file_table.c:465\n   task_work_run+0x150/0x240 kernel/task_work.c:227\n   resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]\n   exit_to_user_mode_loop+0xd4\n---truncated---"
        }
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      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
            "version": "3.1"
          },
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            {
              "lang": "en",
              "value": "AV:N - The vulnerable code is reached from `mptcp_incoming_options()`/`subflow_check_data_avail()` while processing TCP segments received from the remote peer in softirq context, exactly as shown in the syzbot `tcp_v4_rcv` \u2192 `tcp_rcv_established` \u2192 `tcp_reset` trace. Any host running an MPTCP-enabled service (or connecting to an attacker-controlled MPTCP server) is exposed over routed IP with no locality requirement.\nAC:L - The attacker controls both sides of the race: it clears `allow_infinite_fallback` on demand by withholding DATA_ACKs (forcing `__mptcp_retrans()`) or by initiating an MP_JOIN (`mptcp_subflow_joined()`), and simultaneously forces the fallback attempt by sending a segment with no MP_CAPABLE, no DSS, or a bad DSS checksum. The `check_fully_established()` path needs no race window at all \u2014 the `mptcp_do_fallback()` call there is unconditional, so the WARN fires deterministically once `allow_infinite_fallback` is false.\nPR:N - No credentials are required \u2014 the attacker only needs to be the peer of an MPTCP connection, which an unauthenticated remote client obtains by connecting to an MPTCP-enabled listener, and all of this happens in the transport layer well before any application-level authentication.\nUI:N - The entire sequence is driven by attacker-sent TCP segments handled in softirq on an already-established connection; no action by a local user or administrator is needed.\nS:U - The corrupted state (`msk` fallback flags, subflow mappings, receive queue) and the resulting warning/crash are confined to the kernel network stack, the same security authority as the vulnerable component. No VM, IOMMU, or sandbox boundary is crossed.\nC:N - The forged dummy mapping is bounded by `skb-\u003elen` of an attacker-supplied packet and all subsequent accounting stays within the received skb, so no kernel memory is read out of bounds and no data the attacker did not already possess is disclosed.\nI:L - When the fallback silently no-ops, `subflow_check_data_avail()` still installs a forged mapping at `msk-\u003eack_seq` and accepts a payload that failed DSS validation/checksum, bypassing RFC 8684\u0027s data-level integrity check and interleaving unvalidated bytes with correctly-mapped data from other subflows; the `mptcp_finish_join()` and `mptcp_update_infinite_map()` races likewise desynchronize the two peers\u0027 data streams. The modification is real but the attacker cannot choose which kernel structures or how much of the stream is corrupted.\nA:H - The bug is a remotely triggerable `WARN_ON_ONCE` in softirq context, which is a full kernel panic on the many builds that set `panic_on_warn` (cloud, hardened distro, Android, automotive), and the fix itself notes the connection is left in an inconsistent state that pre-fix lacked the RFC-mandated subflow reset, wedging or tearing down the MPTCP connection. The trigger is repeatable across connections by an unauthenticated peer."
            }
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        "dateUpdated": "2026-08-05T12:02:21.965Z",
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        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/5586518bec27666c747cd52aabb62d485686d0bf"
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        {
          "url": "https://git.kernel.org/stable/c/75a4c9ab8a7af0d76b31ccd1188ed178c38b35d2"
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        {
          "url": "https://git.kernel.org/stable/c/f8a1d9b18c5efc76784f5a326e905f641f839894"
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      "title": "mptcp: make fallback action and fallback decision atomic",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38491",
    "datePublished": "2025-07-28T11:21:59.852Z",
    "dateReserved": "2025-04-16T04:51:24.021Z",
    "dateUpdated": "2026-08-05T12:02:21.965Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-38491",
      "date": "2026-08-07",
      "epss": "0.00195",
      "percentile": "0.09442"
    },
    "microsoft_vex": {
      "current_release_date": "2026-03-31T15:05:15.000Z",
      "cve": "CVE-2025-38491",
      "id": "msrc_CVE-2025-38491",
      "initial_release_date": "2025-07-02T00:00:00.000Z",
      "product_status:fixed": "1",
      "product_status:known_affected": "5",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "mptcp: make fallback action and fallback decision atomic",
      "url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2025-38491.json",
      "version": "4"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-38491\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-07-28T12:15:31.240\",\"lastModified\":\"2026-07-30T06:23:21.340\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmptcp: make fallback action and fallback decision atomic\\n\\nSyzkaller reported the following splat:\\n\\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback net/mptcp/protocol.h:1223 [inline]\\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback net/mptcp/protocol.h:1244 [inline]\\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_established net/mptcp/options.c:982 [inline]\\n  WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153\\n  Modules linked in:\\n  CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324dba #20 PREEMPT(voluntary)\\n  Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\\n  RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline]\\n  RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline]\\n  RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline]\\n  RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153\\n  Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 \u003c0f\u003e 0b 90 e9 b8 f4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00\\n  RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246\\n  RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45\\n  RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001\\n  RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000\\n  R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000\\n  R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000\\n  FS:  00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000\\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\\n  CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0\\n  Call Trace:\\n   \u003cIRQ\u003e\\n   tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432\\n   tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975\\n   tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166\\n   tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925\\n   tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363\\n   ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205\\n   ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233\\n   NF_HOOK include/linux/netfilter.h:317 [inline]\\n   NF_HOOK include/linux/netfilter.h:311 [inline]\\n   ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254\\n   dst_input include/net/dst.h:469 [inline]\\n   ip_rcv_finish net/ipv4/ip_input.c:447 [inline]\\n   NF_HOOK include/linux/netfilter.h:317 [inline]\\n   NF_HOOK include/linux/netfilter.h:311 [inline]\\n   ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567\\n   __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975\\n   __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088\\n   process_backlog+0x301/0x1360 net/core/dev.c:6440\\n   __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453\\n   napi_poll net/core/dev.c:7517 [inline]\\n   net_rx_action+0xb44/0x1010 net/core/dev.c:7644\\n   handle_softirqs+0x1d0/0x770 kernel/softirq.c:579\\n   do_softirq+0x3f/0x90 kernel/softirq.c:480\\n   \u003c/IRQ\u003e\\n   \u003cTASK\u003e\\n   __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407\\n   local_bh_enable include/linux/bottom_half.h:33 [inline]\\n   inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524\\n   mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985\\n   mptcp_check_listen_stop net/mptcp/mib.h:118 [inline]\\n   __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000\\n   mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066\\n   inet_release+0xed/0x200 net/ipv4/af_inet.c:435\\n   inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487\\n   __sock_release+0xb3/0x270 net/socket.c:649\\n   sock_close+0x1c/0x30 net/socket.c:1439\\n   __fput+0x402/0xb70 fs/file_table.c:465\\n   task_work_run+0x150/0x240 kernel/task_work.c:227\\n   resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]\\n   exit_to_user_mode_loop+0xd4\\n---truncated---\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mptcp: hacer que la acci\u00f3n y la decisi\u00f3n de fallback sean at\u00f3micas Syzkaller inform\u00f3 del siguiente splat: WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_established net/mptcp/options.c:982 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Modules linked in: CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324dba #20 PREEMPT(voluntary) Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline] RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 \u0026lt;0f\u0026gt; 0b 90 e9 b8 f4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00 RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45 RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001 RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000 FS: 00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0 Call Trace:  tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432 tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975 tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166 tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925 tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363 ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:469 [inline] ip_rcv_finish net/ipv4/ip_input.c:447 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088 process_backlog+0x301/0x1360 net/core/dev.c:6440 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453 napi_poll net/core/dev.c:7517 [inline] net_rx_action+0xb44/0x1010 net/core/dev.c:7644 handle_softirqs+0x1d0/0x770 kernel/softirq.c:579 do_softirq+0x3f/0x90 kernel/softirq.c:480   __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524 mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985 mptcp_check_listen_stop net/mptcp/mib.h:118 [inline] __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000 mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066 inet_release+0xed/0x200 net/ipv4/af_inet.c:435 inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487 __sock_release+0xb3/0x270 net/socket.c:649 sock_close+0x1c/0x30 net/socket.c:1439 __fput+0x402/0xb70 fs/file_table.c:465 task_work_run+0x150/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xd4 ---truncated---\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/mptcp/options.c\",\"net/mptcp/protocol.c\",\"net/mptcp/protocol.h\",\"net/mptcp/subflow.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"0530020a7c8f2204e784f0dbdc882bbd961fdbde\",\"lessThan\":\"5586518bec27666c747cd52aabb62d485686d0bf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0530020a7c8f2204e784f0dbdc882bbd961fdbde\",\"lessThan\":\"75a4c9ab8a7af0d76b31ccd1188ed178c38b35d2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0530020a7c8f2204e784f0dbdc882bbd961fdbde\",\"lessThan\":\"54999dea879fecb761225e28f274b40662918c30\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0530020a7c8f2204e784f0dbdc882bbd961fdbde\",\"lessThan\":\"1d82a8fe6ee4afdc92f4e8808c9dad2a6095bbc5\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0530020a7c8f2204e784f0dbdc882bbd961fdbde\",\"lessThan\":\"f8a1d9b18c5efc76784f5a326e905f641f839894\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"609937aa962a62e93acfc04dd370b665e6152dfb\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6654efe264b014d8ea9fc38f79efb568b1b79069\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"5.10.228\",\"lessThan\":\"5.11\",\"versionType\":\"semver\",\"status\":\"affected\"},{\"version\":\"5.15.169\",\"lessThan\":\"5.16\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/mptcp/options.c\",\"net/mptcp/protocol.c\",\"net/mptcp/protocol.h\",\"net/mptcp/subflow.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.19\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.19\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.149\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.101\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.40\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.15.8\",\"lessThanOrEqual\":\"6.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.16\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]},{\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\",\"affectedData\":[{\"vendor\":\"Siemens\",\"product\":\"SIMATIC CN 4100\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"V5.0\",\"versionType\":\"custom\",\"status\":\"affected\"}]}]}],\"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:N/S:U/C:N/I:L/A:H\",\"baseScore\":8.2,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":4.2},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-667\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.10.228\",\"versionEndExcluding\":\"5.11\",\"matchCriteriaId\":\"7CEF9F93-A67A-45C9-9C51-0024664ACC19\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.15.169\",\"versionEndExcluding\":\"5.16\",\"matchCriteriaId\":\"9C85693E-DA17-43CB-991E-0810328B64A7\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.19\",\"versionEndExcluding\":\"6.1.149\",\"matchCriteriaId\":\"C1860945-7136-4B12-9B55-D522EF9C2FFD\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.101\",\"matchCriteriaId\":\"686C7A1C-35F3-495D-9825-94B5BCED2705\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.40\",\"matchCriteriaId\":\"0099D5A4-B157-4D36-8858-982C7D579030\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.15.8\",\"matchCriteriaId\":\"C7AFE5B0-F3B1-4D30-B8BF-EDA0385C4746\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"6D4894DB-CCFE-4602-B1BF-3960B2E19A01\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"09709862-E348-4378-8632-5A7813EDDC86\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"415BF58A-8197-43F5-B3D7-D1D63057A26E\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"A0517869-312D-4429-80C2-561086E1421C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"85421F4E-C863-4ABF-B4B4-E887CC2F7F92\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.16:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"3827F0D4-5FEE-4181-B267-5A45E7CA11FC\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"FA6FEEC2-9F11-4643-8827-749718254FED\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1d82a8fe6ee4afdc92f4e8808c9dad2a6095bbc5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/54999dea879fecb761225e28f274b40662918c30\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/5586518bec27666c747cd52aabb62d485686d0bf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/75a4c9ab8a7af0d76b31ccd1188ed178c38b35d2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f8a1d9b18c5efc76784f5a326e905f641f839894\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://cert-portal.siemens.com/productcert/html/ssa-032379.html\",\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-30T09:07:56+00:00",
      "cve": "CVE-2025-38491",
      "id": "CVE-2025-38491",
      "initial_release_date": "2025-07-28T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mptcp: make fallback action and fallback decision atomic",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-38491.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-19T17:49:08Z",
      "cve": "CVE-2025-38491",
      "id": "CVE-2025-38491",
      "initial_release_date": "2025-07-28T23:22:29Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "467",
      "product_status:known_not_affected": "281",
      "product_status:recommended": "508",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2025-38491",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-38491.json",
      "version": "56"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

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.


Detection rules are retrieved from Rulezet.