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CVE-2026-43198

tcp: fix potential race in tcp_v6_syn_recv_sock()

Published: 5/6/2026 Last updated: 5/11/2026 Reserved: 5/1/2026

In the Linux kernel, the following vulnerability has been resolved: tcp: fix potential race in tcp_v6_syn_recv_sock() Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock() is done too late. After tcp_v4_syn_recv_sock(), the child socket is already visible from TCP ehash table and other cpus might use it. Since newinet->pinet6 is still pointing to the listener ipv6_pinfo bad things can happen as syzbot found. Move the problematic code in tcp_v6_mapped_child_init() and call this new helper from tcp_v4_syn_recv_sock() before the ehash insertion. This allows the removal of one tcp_sync_mss(), since tcp_v4_syn_recv_sock() will call it with the correct context.

CNA assigner: Linux (416baaa9-dc9f-4396-8d5f-8c081fb06d67) Requested by: n/a

Metrics

Version Score Severity Vector String
3.1 9.8 Critical CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Opam packages affected (29)

albatross cdrom conf-bpftool conf-libbpf conf-linux-libc-dev core core_unix hvsock mirage-block-unix mm ocaml-probes ortools_solvers orun rawlink rawlink-eio rawlink-lwt restricted shell solo5 solo5-bindings-hvt solo5-bindings-spt solo5-cross-aarch64 solo5-kernel-ukvm tracy-client tuntap uring vhd-format vhd-format-lwt xapi-stdext-unix

Products affected (4)

Product Vendor Version
Linux Linux 5.4.2.2
Linux Linux 5.3.6.9
Linux Linux 12.2(12g)
Linux Linux 12.2(27)

References (6)