EUVD-2026-27757
GHSA-rhcj-6wxj-r34p
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
4DescriptionNVD
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.
AnalysisAI
Race condition in Linux kernel TCP/IPv6 stack allows remote unauthenticated attackers to trigger use-after-free conditions during IPv6-mapped IPv4 socket creation, potentially achieving arbitrary code execution or denial of service. The flaw occurs in tcp_v6_syn_recv_sock() where child socket visibility in the TCP hash table races with incomplete IPv6 structure initialization, causing other CPUs to access invalid memory via newinet->pinet6 pointing to listener data. …
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RemediationAI
Within 24 hours: Identify all Linux systems running kernel versions prior to 6.18.16, 6.19.6, or 7.0 and assess which handle IPv6-mapped IPv4 traffic. Within 7 days: Apply vendor-released patches to kernel versions 6.18.16, 6.19.6, or 7.0 (or later) across production and staging environments, prioritizing customer-facing and data-processing systems. …
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