CVE-2026-43198 POC (Proof-of-Concept)

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.

Published: 2026-05-06

CVSS: 9.8

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Download CVE-2026-43198 POC (Proof-of-Concept) here:

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https://hokyo.gr/poc-634-cve-2026-43575/

https://hokyo.gr/poc-474-cve-2026-43133/

https://hokyo.gr/poc-188-cve-2026-7644/

https://hokyo.gr/poc-34-cve-2026-31700/