In the Linux kernel, the following vulnerability has been resolved: ipv6: fix possible infinite loop in fib6_select_path() Found while auditing the… (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
AI Analysis
Technical Summary
The Linux kernel IPv6 subsystem contained a flaw in fib6_select_path() where writers holding the tb6_lock could remove list entries without waiting for RCU readers, causing the fib6_siblings linked list to appear circular and resulting in a potential infinite loop during route selection. The fix applies a pattern previously used in a similar function (fib6_info_uses_dev()) to ensure that an inside-loop check reliably detects list detachment by WRITE_ONCE() updating a sibling count before removal. This prevents the softirq-side walker from looping indefinitely.
Potential Impact
The vulnerability could cause the kernel to enter an infinite loop during IPv6 route selection, potentially leading to a denial of service by consuming CPU resources indefinitely. There is no indication of code execution or privilege escalation from the provided data.
Mitigation Recommendations
A fix for this vulnerability has been applied in the Linux kernel. Since this is a kernel-level issue, users should update to a kernel version that includes this patch once available. Patch status is not yet confirmed from the provided data; check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply updates accordingly.
In the Linux kernel, the following vulnerability has been resolved: ipv6: fix possible infinite loop in fib6_select_path() Found while auditing the… (CVE-2026-63968)
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
CVSS v3.1
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel IPv6 subsystem contained a flaw in fib6_select_path() where writers holding the tb6_lock could remove list entries without waiting for RCU readers, causing the fib6_siblings linked list to appear circular and resulting in a potential infinite loop during route selection. The fix applies a pattern previously used in a similar function (fib6_info_uses_dev()) to ensure that an inside-loop check reliably detects list detachment by WRITE_ONCE() updating a sibling count before removal. This prevents the softirq-side walker from looping indefinitely.
Potential Impact
The vulnerability could cause the kernel to enter an infinite loop during IPv6 route selection, potentially leading to a denial of service by consuming CPU resources indefinitely. There is no indication of code execution or privilege escalation from the provided data.
Mitigation Recommendations
A fix for this vulnerability has been applied in the Linux kernel. Since this is a kernel-level issue, users should update to a kernel version that includes this patch once available. Patch status is not yet confirmed from the provided data; check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply updates accordingly.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-c2hg-pgqh-6wp2
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-63968"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27aa2a4a8d598912e8ca
Added to database: 07/19/2026, 19:38:18 UTC
Last enriched: 07/19/2026, 20:05:11 UTC
Last updated: 07/20/2026, 21:51:48 UTC
Views: 11
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