tcp: fix potential race in tcp_v6_syn_recv_sock()_CVE-2026-43198

9.8 / 10

CRITICAL

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

Description

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.

AI Analysis

Potential race condition in tcp_v6_syn_recv_sock() function

Basic Information

ID CVE-2026-43198

Source Linux

Published May 6, 2026 at 11:28

Modified May 8, 2026 at 12:41

Affected Product

Vendor Linux

Product Linux

Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2

Affected Versions Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Linux Linux 2.6.12

AI Assessment

AI Score 9.8 / 10

AI Severity Critical

Vendor Linux

Product Linux Kernel

Version 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, 2.6.12

References

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    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix potential race in tcp_v6_syn_recv_sock()\n\nCode in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock()\nis done too late.\n\nAfter tcp_v4_syn_recv_sock(), the child socket is already visible\nfrom TCP ehash table and other cpus might use it.\n\nSince newinet->pinet6 is still pointing to the listener ipv6_pinfo\nbad things can happen as syzbot found.\n\nMove the problematic code in tcp_v6_mapped_child_init()\nand call this new helper from tcp_v4_syn_recv_sock() before\nthe ehash insertion.\n\nThis allows the removal of one tcp_sync_mss(), since\ntcp_v4_syn_recv_sock() will call it with the correct\ncontext.",
    "published": "2026-05-06T11:28:05.569Z",
    "modified": "2026-05-08T12:41:10.445Z",
    "type": "cve",
    "title": "tcp: fix potential race in tcp_v6_syn_recv_sock()",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/fe89b2f05b854847784f91127319172945c1fadd\nhttps://git.kernel.org/stable/c/7178e2a8027423b2af17ab95df73a749a5b72e5b\nhttps://git.kernel.org/stable/c/858d2a4f67ff69e645a43487ef7ea7f28f06deae",
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