CVE-2026-63968
Received Received - Intake

Infinite Loop in Linux Kernel IPv6 Routing

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: fix possible infinite loop in fib6_select_path() Found while auditing the same pattern Sashiko reported in rt6_fill_node() [1]. Apply the same fix as commit f8d8ce1b515a ("ipv6: fix possible infinite loop in fib6_info_uses_dev()"). Writers holding tb6_lock can list_del_rcu(&first->fib6_siblings) without waiting for RCU readers; first->fib6_siblings.next then still points into the old ring and this softirq-side walker never reaches &first->fib6_siblings as its terminator. fib6_purge_rt() always WRITE_ONCE()s first->fib6_nsiblings to 0 before list_del_rcu(), so an inside-loop check is a reliable detach signal. [1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev

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Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-63968
EUVD
EUVD-2026-45741

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 in the Linux kernel involves a possible infinite loop in the IPv6 routing subsystem, specifically in the fib6_select_path() function. The issue occurs when writers modify routing table entries without proper synchronization, causing softirq-side walkers to loop indefinitely while traversing a linked list of routing entries.

Detection Guidance

This vulnerability is specific to the Linux kernel's IPv6 routing implementation and may not have direct detection commands. Focus on kernel version checks and monitoring for system hangs or crashes related to IPv6 routing. Use 'uname -a' to check kernel version and 'dmesg' to look for kernel errors.

Impact Analysis

This vulnerability could lead to system hangs or crashes due to infinite loops in kernel networking code. It may cause network connectivity issues, degraded performance, or complete system unresponsiveness, particularly in systems heavily using IPv6 routing.

Compliance Impact

This vulnerability is a kernel-level issue in the Linux IPv6 networking stack that could lead to a denial-of-service condition via an infinite loop. It does not directly affect data confidentiality or integrity but may impact system availability. Compliance with standards like GDPR or HIPAA typically requires maintaining system availability and security, so this issue could indirectly affect compliance if it causes prolonged downtime or service disruptions.

Mitigation Strategies

Update the Linux kernel to the latest stable version that includes the fix for CVE-2026-63968. Monitor kernel patches and apply them promptly to address the infinite loop issue in fib6_select_path().

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