CVE-2026-63968

ipv6: fix possible infinite loop in fib6_select_path()

State: Published
Severity: 7.5 High
Published: Jul 19, 2026
Updated: Oct 19, 2026
Reserved: Jul 19, 2026

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

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	Linux

Weaknesses

CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')

Affected Products

Product	Versions
LinuxLinux	d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2 to before 3948a7d92f7678e89e1776bb2d169afcad63b1aeAffected 52da02521ede55fb86546c3fffd9377b3261b91f to before c87cd3cb309634bc8f50a54e2079424f219ac21fAffected 34a949e7a0869dfa31a40416d2a56973fae1807b to before 0f7b73c3452635de83b8711b31abdda8e49aad7bAffected d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before ab9a10969a907b472a0196d999c08ff7144172e3Affected d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before 9b9d5bd6e3d4c9cecab5407604b690684b2532d2Affected d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before 9c7da87c2dc860bb17ca1ece942495d28b1ce3b9Affected 11edcd026012ac18acee0f1514db3ed1b160fc6fAffected 6.1.128 to before 6.1.176Affected 6.6.75 to before 6.6.143Affected 6.12.2 to before 6.12.93Affected 6.11.11 to before 6.12Affected
LinuxLinux	6.13Affected before 6.13Not affected 6.1.176 through 6.1.Not affected 6.6.143 through 6.6.Not affected 6.12.93 through 6.12.Not affected 6.18.35 through 6.18.Not affected 7.0.12 through 7.0.*Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2 to before 3948a7d92f7678e89e1776bb2d169afcad63b1aeAffected
52da02521ede55fb86546c3fffd9377b3261b91f to before c87cd3cb309634bc8f50a54e2079424f219ac21fAffected
34a949e7a0869dfa31a40416d2a56973fae1807b to before 0f7b73c3452635de83b8711b31abdda8e49aad7bAffected
d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before ab9a10969a907b472a0196d999c08ff7144172e3Affected
d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before 9b9d5bd6e3d4c9cecab5407604b690684b2532d2Affected
d9ccb18f83ea2bb654289b6ecf014fd267cc988b to before 9c7da87c2dc860bb17ca1ece942495d28b1ce3b9Affected
11edcd026012ac18acee0f1514db3ed1b160fc6fAffected
6.1.128 to before 6.1.176Affected
6.6.75 to before 6.6.143Affected
6.12.2 to before 6.12.93Affected
6.11.11 to before 6.12Affected

LinuxLinux

6.13Affected
before 6.13Not affected
6.1.176 through 6.1.*Not affected
6.6.143 through 6.6.*Not affected
6.12.93 through 6.12.*Not affected
6.18.35 through 6.18.*Not affected
7.0.12 through 7.0.*Not affected
7.1 and laterNot affected

References

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