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CVE-2026-63968

HIGHCVSS 7.5/10EPSS 0.65%

Last modified

CVE-2026-63968 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.65% chance of exploitation in the next 30 days.

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

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.65%

47.4th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2, < 3948a7d92f7678e89e1776bb2d169afcad63b1ae; >= 52da02521ede55fb86546c3fffd9377b3261b91f, < c87cd3cb309634bc8f50a54e2079424f219ac21f; >= 34a949e7a0869dfa31a40416d2a56973fae1807b, < 0f7b73c3452635de83b8711b31abdda8e49aad7b; >= d9ccb18f83ea2bb654289b6ecf014fd267cc988b, < ab9a10969a907b472a0196d999c08ff7144172e3; >= d9ccb18f83ea2bb654289b6ecf014fd267cc988b, < 9b9d5bd6e3d4c9cecab5407604b690684b2532d2; >= d9ccb18f83ea2bb654289b6ecf014fd267cc988b, < 9c7da87c2dc860bb17ca1ece942495d28b1ce3b9; 11edcd026012ac18acee0f1514db3ed1b160fc6f; >= 6.1.128, < 6.1.176; >= 6.6.75, < 6.6.143; >= 6.12.2, < 6.12.93; >= 6.11.11, < 6.12
LinuxLinux6.13

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-63968?
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
How severe is CVE-2026-63968?
CVE-2026-63968 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.65% probability of exploitation in the next 30 days.
How do I fix CVE-2026-63968?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST