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Linux security advisory (AV26-1108)

MediumCanadian Centre for Cyber Security · Canadian Centre for Cyber Security·

At a glance

Severity
Medium
Used in attacks
Not on CISA’s list
Flaws named
CVE-2026-98432
Vendors and products
Linux
Reported by
1 outlet

As of October 15, 2026, Linux is affected by a vulnerability in the following product:

  • Linux
    • Prior to 5.10.272
    • Prior 5.15.223
    • Prior to 6.1.190
    • Prior to 6.6.159
    • Prior to 6.12.113
    • Prior to 6.18.56
    • Prior to 7.2.10
    • Prior to 7.3

The Cyber Centre encourages users and administrators to review the provided web links and apply any necessary updates as they become available.

Originally published by Canadian Centre for Cyber Security. © Canadian Centre for Cyber Security. Written by Canadian Centre for Cyber Security.

Read at cyber.gc.ca ↗Official Source

Vulnerabilities referenced

  • CVE-2026-98432Not scored yet

    Product not named yet

    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() duplica

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Coverage

One outlet has carried this so far.

  1. Canadian Centre for Cyber Security ↗Official SourceFirst reported

    2026-10-30 21:34 UTC

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