VulnerabilityPublished 19 Jul 2026

CVE-2026-63969: Linux kernel · ipv6: fix possible infinite loop in rt6_fill_node()

Source GCVE Database

Not known to be exploited.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Medium

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-wc3h-5qqj-xwhm

What to do

AI-suggested

A fix has been applied to the Linux kernel to resolve this issue. Users should update to a kernel version that includes this patch. Since this is a kernel-level vulnerability, applying the official kernel update from the vendor or distribution is the recommended remediation.

Description

A vulnerability in the Linux kernel's IPv6 implementation could cause a possible infinite loop in the rt6_fill_node() function. This issue arises due to improper handling of the fib6_siblings list during route deletion, potentially leading to a CPU stall. The vulnerability has been resolved by applying a fix that ensures reliable detection of route detachment within the loop.

Impact

This vulnerability could cause a CPU stall due to an infinite loop in the IPv6 routing code, potentially impacting system stability and availability. There is no indication of code execution or privilege escalation from the provided data.

Summary

The Linux kernel contained a vulnerability in the IPv6 routing code where writers holding the tb6_lock could remove a route from the fib6_siblings list without waiting for RCU readers to complete. This caused the rt->fib6_siblings.next pointer to still reference the old list ring, resulting in the softirq-side walker failing to reach the list head and causing an infinite loop and CPU stall. The fix applies a check on rt->fib6_nsiblings, which is set to zero before list_del_rcu(), serving as a reliable signal to detach from the loop and prevent the infinite loop condition.

References

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