CVE intelligence

CVE-2026-72421

Vulnerability intelligence

Published Aug 15, 2026Sources checked Oct 8, 2026

10.0CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-72421 and is rated Critical severity with a CVSS score of 10.0. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.6%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-72421?

In the Linux kernel, the following vulnerability has been resolved:

ipv4: fib: Don't ignore error route in local/main tables.

When CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added, fib_lookup() performs route lookup directly on two tables.

Since the first lookup does not properly bail out, the result of an error route in the merged local/main table could be overwritten by another route in the default table:

# unshare -n # ip link set lo up # ip route add 192.168.0.0/24 dev lo table 253 # ip route add unreachable 192.168.0.0/24 # ip route get 192.168.0.1 192.168.0.1 dev lo table default uid 0 cache <local>

Once a random rule is added, the error route is respected:

# ip rule add table 0 # ip rule del table 0 # ip route get 192.168.0.1 RTNETLINK answers: No route to host

Let's fix the inconsistent behaviour.

Source: NVD