CVE-2026-43198

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < aef4a9ae95d1bc4f7897065011e6261026719aebaffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < dad1fe7db6c6519138430ac8f5e589c18f83bfc9affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a7e761ba55efaa9c49e0afdd304bb78167af3429affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cd644e6dc72eec8d9d988717ea1c54f8668ded69affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 9ed654e340f4c73bc6f0af2fbc90ac293e645ce0affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < fe89b2f05b854847784f91127319172945c1faddaffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7178e2a8027423b2af17ab95df73a749a5b72e5baffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 858d2a4f67ff69e645a43487ef7ea7f28f06deaeaffected
LinuxLinux2.6.12affected
LinuxLinux0 < 2.6.12unaffected
LinuxLinux5.10.270 <= 5.10.*unaffected
LinuxLinux5.15.221 <= 5.15.*unaffected
LinuxLinux6.1.188 <= 6.1.*unaffected
LinuxLinux6.6.157 <= 6.6.*unaffected
LinuxLinux6.12.110 <= 6.12.*unaffected
LinuxLinux6.18.16 <= 6.18.*unaffected
LinuxLinux6.19.6 <= 6.19.*unaffected
LinuxLinux7.0 <= *unaffected

Weaknesses

ADP Enrichment

kernel: tcp: fix potential race in tcp_v6_syn_recv_sock()

Additional References

References