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.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data.
No data.
No data available yet.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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Sat, 15 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | ipv4: fib: Don't ignore error route in local/main tables. | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T05:56:40.466Z
Reserved: 2026-08-09T03:40:39.927Z
Link: CVE-2026-72421
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T06:22:15.867
Modified: 2026-08-15T06:22:15.867
Link: CVE-2026-72421
Redhat
No data.
OpenCVE Enrichment
No data.
No weakness.