{"id":"CVE-2026-98276","published":"2026-10-06T09:18:17.360","lastModified":"2026-10-07T07:17:07.640","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lock the socket in sock_gettstamp()\n\nsk->sk_flags must only be changed while holding the socket lock,\nbecause sock_set_flag() and sock_reset_flag() use non atomic\noperations (__set_bit() and __clear_bit()).\n\nsock_gettstamp() is one of the last places where a bit of sk->sk_flags\nis changed from a syscall without owning the socket lock, through\nsock_enable_timestamp(sk, SOCK_TIMESTAMP).\n\nsk_set_memalloc() and sk_clear_memalloc() also change sk->sk_flags\nwithout the socket lock, but their callers (nbd, iscsi_tcp, nvme-tcp,\nsunrpc, wireguard) need a careful audit, this will be addressed in a\nseparate patch.\n\nJungwoo Lee and Wongi Lee reported an UDP socket use-after-free\ncaused by this bug: a SIOCGSTAMPNS_NEW ioctl racing with bind()\ncan cancel the SOCK_RCU_FREE bit that udp_lib_get_port() just set,\nbecause both threads perform a read-modify-write on the same word.\n\n  CPU 0 (bind)                        CPU 1 (SIOCGSTAMPNS_NEW)\n  --------------------------------    ----------------------------\n  read sk_flags = F                   read sk_flags = F\n  compute F | BIT(SOCK_RCU_FREE)      compute F | BIT(SOCK_TIMESTAMP)\n  store F | BIT(SOCK_RCU_FREE)\n  sk_add_node_rcu(sk, ...)\n                                      store F | BIT(SOCK_TIMESTAMP)\n\nAfter the lost update, SOCK_RCU_FREE is clear while the socket is\nvisible to lockless UDP receive lookups. sk_destruct() then frees\nthe socket immediately instead of waiting for a RCU grace period,\nwhile the receive path still holds a reference-less pointer to it:\n\n BUG: KASAN: slab-use-after-free in ipv4_pktinfo_prepare+0x30/0x410\n Read of size 8 at addr ffff888008806610 by task exploit/207\n CPU: 0 UID: 1000 PID: 207 Comm: exploit Not tainted 6.12.95+ #1\n  ipv4_pktinfo_prepare+0x30/0x410\n  udp_queue_rcv_one_skb+0x51c/0x1180\n  udp_unicast_rcv_skb+0x109/0x350\n  ip_protocol_deliver_rcu+0x14b/0x310\n  ip_local_deliver_finish+0x29d/0x390\n  ip_local_deliver+0x24d/0x2a0\n\nOnly grab the socket lock when SOCK_TIMESTAMP has to be set,\nto keep the common case lockless.","cvssScore":7.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f","tags":[]},{"url":"https://git.kernel.org/stable/c/18899e2e4023369a8f7739c2255a59a9748d8d17","tags":[]},{"url":"https://git.kernel.org/stable/c/1f73253add8365d0dad0a4f421acaa8c21d20cef","tags":[]},{"url":"https://git.kernel.org/stable/c/3b12d3967e96f1b7b977d9fc352ae29a1b299a82","tags":[]},{"url":"https://git.kernel.org/stable/c/88c804847dd87dc613b771b392ccecdb94725032","tags":[]},{"url":"https://git.kernel.org/stable/c/899650bbf985b7bfd2a7b808357df9b16e6d6959","tags":[]},{"url":"https://git.kernel.org/stable/c/9ed55f3dbef4f4adfe65eb03b0c35c53229a8490","tags":[]},{"url":"https://git.kernel.org/stable/c/d9f96bc2d822501f84d1caa6275a2c6b316ca2c4","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"The Linux kernel contains a race condition in sock_gettstamp() where socket flags are modified without proper locking, leading to potential use-after-free conditions in UDP sockets when SIOCGSTAMPNS_NEW ioctl races with bind() operations. This vulnerability allows for memory corruption and system instability.","exploitability":"Exploitation requires precise timing of concurrent bind() and SIOCGSTAMPNS_NEW operations on the same UDP socket, making it moderately difficult but possible with specific workload conditions.","blast_radius":"The vulnerability affects all UDP socket operations that use the SIOCGSTAMPNS_NEW ioctl, potentially causing system crashes, memory corruption, or denial of service across network services using UDP sockets.","remediation":"Apply kernel patch for Linux kernel version 6.10-rc1 or later which includes the fix for sock_gettstamp() socket locking issue.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["network","kernel","race-condition"],"model":"garnet-coder","analyzedAt":"2026-10-14T09:04:10.680Z"}}