#CVE-2026-98432

NVD の情報

In the Linux kernel, the following vulnerability has been resolved: ipv4: free inet_opt and ireq_opt after an RCU grace period tcp_v4_syn_recv_sock() transfers ownership of ireq->ireq_opt to the child socket (newinet->inet_opt) without copying it. Another cpu can concurrently process a retransmitted SYN for the same request socket, and send a SYNACK from tcp_check_req(). tcp_v4_send_synack() and inet_csk_route_req() read ireq->ireq_opt under rcu_read_lock() only, and ip_build_and_send_pkt() and ip_options_build() then read opt->optlen twice. Note that the SYNACK timer itself is not an issue: it holds a reference on its request socket, and inet_csk_reqsk_queue_drop() calls timer_delete_sync() before the child can be freed. Since commit 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table"), request sockets are processed without holding the listener lock, so nothing prevents the child socket from being freed while the SYNACK is still being built. TCP child sockets do not have SOCK_RCU_FREE, and inet_sock_destruct() frees inet_opt with a plain kfree(), leading to a use-after-free in ip_options_build(). A similar issue exists with request socket migration (net.ipv4.tcp_migrate_req=1, or a BPF_SK_REUSEPORT_SELECT_OR_MIGRATE program). reqsk_timer_handler() clones the request socket with inet_reqsk_clone(), so that the old request socket and its clone share the same ireq_opt, then reqsk_migrate_reset() clears the pointer in the old one. Another cpu holding a reference on the old request socket can still be using these options (sending a SYNACK, or creating a child in tcp_v4_syn_recv_sock()) when the clone is freed, and tcp_v4_reqsk_destructor() also uses a plain kfree(). Readers already use RCU, and other paths replacing inet_opt (do_ip_setsockopt(), cipso_v4_sock_setattr()...) already use kfree_rcu(). Use kfree_rcu() in inet_sock_destruct() and tcp_v4_reqsk_destructor() as well. IPv6 is not affected by the first issue, because tcp_v6_syn_recv_sock() duplicates the options. tcp_v6_reqsk_destructor() has the same migration issue with ipv6_opt, which is only set by CALIPSO. This will be addressed in a separate patch.

公開日

2026-10-15

最終更新（NVD）

2026-10-24

NVD の状態

Received

深刻度（CVSS）

• 9.8 CriticalCVSS 3.1／副／評価：416baaa9-dc9f-4396-8d5f-8c081fb06d67CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

悪用の状況

CISA KEV には掲載されていません（掲載されていないことは、悪用されていないことの証明ではありません）。

EPSS：今後30日に悪用される推定確率 0.39%（全体の上位 67.2%、評価日 2026-10-29）

解消方法

• 解消方法の情報なし

「NVD の条件から推定」は、NVD が影響ありとする版の上限から読み取ったもので、修正版とは限りません。「解消方法の情報なし」は、修正が無いという意味ではありません。必ずベンダーの公告で確認してください。

編集部の記載（レポート掲載時）

レポートの編集部がベンダー公告などから転記した内容です。検証済みの値ではないため、必ず出典で確認してください。

参照（NVD）

• https://git.kernel.org/stable/c/11a03ce3c4a62d84c10ccdfe47f8075006498568
• https://git.kernel.org/stable/c/26d4c36d318cffbbd160884a0e4cec0da4da4936
• https://git.kernel.org/stable/c/742f73df544e03744f2981c467d6542fe8172a2a
• https://git.kernel.org/stable/c/89b5b1eb7d633c33832b7ff2c02e19a144705036
• https://git.kernel.org/stable/c/95a8c8fa9f27dce64c40c41c062de7728bf34ab5
• https://git.kernel.org/stable/c/a47406c769f72c070386985488f1c4d057df86b2
• https://git.kernel.org/stable/c/b3b027ef0cd322bfa839b9aaf5b27551eea54cf6
• https://git.kernel.org/stable/c/e3f33b0a1d89d738e2b913dab519226eaf76e15b