CVE-2026-64518
Received Received - Intake

Out-of-Bounds Access in Linux Kernel TCP Implementation

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: tcp: Fix out-of-bounds access for twsk in tcp_ao_established_key(). lockdep_sock_is_held() was added in tcp_ao_established_key() by the cited commit. It can be called from tcp_v[46]_timewait_ack() with twsk. Since it does not have sk->sk_lock, the lockdep annotation results in out-of-bound access. $ pahole -C tcp_timewait_sock vmlinux | grep size /* size: 288, cachelines: 5, members: 8 */ $ pahole -C sock vmlinux | grep sk_lock socket_lock_t sk_lock; /* 440 192 */ Let's not use lockdep_sock_is_held() for TCP_TIME_WAIT.

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64518
EUVD
EUVD-2026-48862

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a Linux kernel issue where an out-of-bounds access occurs in the tcp_ao_established_key() function. The problem arises because lockdep_sock_is_held() is called on a tcp_timewait_sock object which lacks the sk_lock member, leading to incorrect memory access.

Detection Guidance

This vulnerability is specific to the Linux kernel's TCP implementation and requires kernel-level inspection. Detection involves checking kernel version and analyzing the tcp_ao_established_key function. Use 'uname -a' to check kernel version and 'grep tcp_ao_established_key /proc/kallsyms' to verify function presence. Kernel debugging tools like 'pahole' can inspect struct sizes but require kernel debug info.

Impact Analysis

This vulnerability could allow an attacker to cause a denial-of-service condition or potentially execute arbitrary code in the Linux kernel. It may lead to system crashes or instability if exploited.

Mitigation Strategies

Immediate mitigation requires updating the Linux kernel to a patched version that resolves this issue. Check your distribution's security advisories for kernel updates. If no patch is available, avoid using TCP authentication options (TCP-AO) until patched. Monitor vendor announcements for updates.

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