{
  "threat_severity" : "Moderate",
  "public_date" : "2025-12-04T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: Linux kernel MPTCP: Privilege escalation or denial of service via use-after-free in timer handling",
    "id" : "2418880",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2418880"
  },
  "cvss3" : {
    "cvss3_base_score" : "6.7",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-366",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nmptcp: fix a race in mptcp_pm_del_add_timer()\nmptcp_pm_del_add_timer() can call sk_stop_timer_sync(sk, &entry->add_timer)\nwhile another might have free entry already, as reported by syzbot.\nAdd RCU protection to fix this issue.\nAlso change confusing add_timer variable with stop_timer boolean.\nsyzbot report:\nBUG: KASAN: slab-use-after-free in __timer_delete_sync+0x372/0x3f0 kernel/time/timer.c:1616\nRead of size 4 at addr ffff8880311e4150 by task kworker/1:1/44\nCPU: 1 UID: 0 PID: 44 Comm: kworker/1:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)}\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025\nWorkqueue: events mptcp_worker\nCall Trace:\n<TASK>\ndump_stack_lvl+0x189/0x250 lib/dump_stack.c:120\nprint_address_description mm/kasan/report.c:378 [inline]\nprint_report+0xca/0x240 mm/kasan/report.c:482\nkasan_report+0x118/0x150 mm/kasan/report.c:595\n__timer_delete_sync+0x372/0x3f0 kernel/time/timer.c:1616\nsk_stop_timer_sync+0x1b/0x90 net/core/sock.c:3631\nmptcp_pm_del_add_timer+0x283/0x310 net/mptcp/pm.c:362\nmptcp_incoming_options+0x1357/0x1f60 net/mptcp/options.c:1174\ntcp_data_queue+0xca/0x6450 net/ipv4/tcp_input.c:5361\ntcp_rcv_established+0x1335/0x2670 net/ipv4/tcp_input.c:6441\ntcp_v4_do_rcv+0x98b/0xbf0 net/ipv4/tcp_ipv4.c:1931\ntcp_v4_rcv+0x252a/0x2dc0 net/ipv4/tcp_ipv4.c:2374\nip_protocol_deliver_rcu+0x221/0x440 net/ipv4/ip_input.c:205\nip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:239\nNF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318\nNF_HOOK+0x30c/0x3a0 include/linux/netfilter.h:318\n__netif_receive_skb_one_core net/core/dev.c:6079 [inline]\n__netif_receive_skb+0x143/0x380 net/core/dev.c:6192\nprocess_backlog+0x31e/0x900 net/core/dev.c:6544\n__napi_poll+0xb6/0x540 net/core/dev.c:7594\nnapi_poll net/core/dev.c:7657 [inline]\nnet_rx_action+0x5f7/0xda0 net/core/dev.c:7784\nhandle_softirqs+0x22f/0x710 kernel/softirq.c:622\n__do_softirq kernel/softirq.c:656 [inline]\n__local_bh_enable_ip+0x1a0/0x2e0 kernel/softirq.c:302\nmptcp_pm_send_ack net/mptcp/pm.c:210 [inline]\nmptcp_pm_addr_send_ack+0x41f/0x500 net/mptcp/pm.c:-1\nmptcp_pm_worker+0x174/0x320 net/mptcp/pm.c:1002\nmptcp_worker+0xd5/0x1170 net/mptcp/protocol.c:2762\nprocess_one_work kernel/workqueue.c:3263 [inline]\nprocess_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346\nworker_thread+0x8a0/0xda0 kernel/workqueue.c:3427\nkthread+0x711/0x8a0 kernel/kthread.c:463\nret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158\nret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n</TASK>\nAllocated by task 44:\nkasan_save_stack mm/kasan/common.c:56 [inline]\nkasan_save_track+0x3e/0x80 mm/kasan/common.c:77\npoison_kmalloc_redzone mm/kasan/common.c:400 [inline]\n__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417\nkasan_kmalloc include/linux/kasan.h:262 [inline]\n__kmalloc_cache_noprof+0x1ef/0x6c0 mm/slub.c:5748\nkmalloc_noprof include/linux/slab.h:957 [inline]\nmptcp_pm_alloc_anno_list+0x104/0x460 net/mptcp/pm.c:385\nmptcp_pm_create_subflow_or_signal_addr+0xf9d/0x1360 net/mptcp/pm_kernel.c:355\nmptcp_pm_nl_fully_established net/mptcp/pm_kernel.c:409 [inline]\n__mptcp_pm_kernel_worker+0x417/0x1ef0 net/mptcp/pm_kernel.c:1529\nmptcp_pm_worker+0x1ee/0x320 net/mptcp/pm.c:1008\nmptcp_worker+0xd5/0x1170 net/mptcp/protocol.c:2762\nprocess_one_work kernel/workqueue.c:3263 [inline]\nprocess_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346\nworker_thread+0x8a0/0xda0 kernel/workqueue.c:3427\nkthread+0x711/0x8a0 kernel/kthread.c:463\nret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158\nret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\nFreed by task 6630:\nkasan_save_stack mm/kasan/common.c:56 [inline]\nkasan_save_track+0x3e/0x80 mm/kasan/common.c:77\n__kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587\nkasan_save_free_info mm/kasan/kasan.h:406 [inline]\npoison_slab_object m\n---truncated---", "A flaw was found in the Linux kernel's Multipath TCP (MPTCP) implementation. A race condition in the `mptcp_pm_del_add_timer()` function allows for a use-after-free vulnerability. This can be exploited by a local attacker to cause a denial of service (DoS), potentially leading to privilege escalation or arbitrary code execution." ],
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2026-05-19T00:00:00Z",
    "advisory" : "RHSA-2026:18134",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.2",
    "package" : "kernel-0:6.12.0-211.7.1.el10_2"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Will not fix",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Will not fix",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Will not fix",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Will not fix",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2025-40257\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-40257\nhttps://lore.kernel.org/linux-cve-announce/2025120433-CVE-2025-40257-53e6@gregkh/T" ],
  "name" : "CVE-2025-40257",
  "csaw" : false
}