Description
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.
References8
- git.kernel.org/stable/c/49eaf1403201357762d745a35882fb734107d763
- git.kernel.org/stable/c/5ae18d87a45698e8244d0fcba64c658c35a7dd3d
- git.kernel.org/stable/c/828fad4fd418bcdb9f5d66fec0d184c52a85ec31
- git.kernel.org/stable/c/9127589aabdee588278e8d0d0bd3709a760a92c8
- git.kernel.org/stable/c/a29e95fbc51e8a1b932773fd0e259b2080881443
- git.kernel.org/stable/c/a668fa160247d7bbe921548cb845f607b8b9305f
- git.kernel.org/stable/c/b72f0db64205d9ce462038ba995d5d31eff32dc1
- git.kernel.org/stable/c/fd25996f57a95d56bc568c89b4921edcf334b7d8
Metrics
- CVSS 3.1
-
10.0
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N - EPSS — exploit probability
- 1% percentile: 48 · as of 11 November 2026
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.