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10.0
CRITICAL CVSS 3.1
CVE-2026-72421
ipv4: fib: Don't ignore error route in local/main tables.
Overview
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.

Details
INFO

Published Date :

Aug. 15, 2026, 6:22 a.m.

Last Modified :

Aug. 17, 2026, 6:19 a.m.

Remotely Exploit :

Yes !

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Impact
Affected Products

The following products are affected by CVE-2026-72421 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 CRITICAL 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
Update the Linux kernel to resolve route lookup inconsistencies when multiple routing tables are enabled.
  • Update the Linux kernel to the latest version.
  • Ensure routing rules are correctly configured.
  • Verify route lookup behavior after updates.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-72421.

URL Resource
https://git.kernel.org/stable/c/49eaf1403201357762d745a35882fb734107d763
https://git.kernel.org/stable/c/5ae18d87a45698e8244d0fcba64c658c35a7dd3d
https://git.kernel.org/stable/c/828fad4fd418bcdb9f5d66fec0d184c52a85ec31
https://git.kernel.org/stable/c/9127589aabdee588278e8d0d0bd3709a760a92c8
https://git.kernel.org/stable/c/a29e95fbc51e8a1b932773fd0e259b2080881443
https://git.kernel.org/stable/c/a668fa160247d7bbe921548cb845f607b8b9305f
https://git.kernel.org/stable/c/b72f0db64205d9ce462038ba995d5d31eff32dc1
https://git.kernel.org/stable/c/fd25996f57a95d56bc568c89b4921edcf334b7d8
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-72421 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-72421 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-72421 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-72421 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 17, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
    Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'a29e95fbc51e8a1b932773fd0e259b2080881443', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '5ae18d87a45698e8244d0fcba64c658c35a7dd3d', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '9127589aabdee588278e8d0d0bd3709a760a92c8', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '49eaf1403201357762d745a35882fb734107d763', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'fd25996f57a95d56bc568c89b4921edcf334b7d8', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '828fad4fd418bcdb9f5d66fec0d184c52a85ec31', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'a668fa160247d7bbe921548cb845f607b8b9305f', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'b72f0db64205d9ce462038ba995d5d31eff32dc1', 'versionType': 'git'}], 'programFiles': ['include/net/ip_fib.h'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.261', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.212', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/net/ip_fib.h'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'a29e95fbc51e8a1b932773fd0e259b2080881443', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '5ae18d87a45698e8244d0fcba64c658c35a7dd3d', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '9127589aabdee588278e8d0d0bd3709a760a92c8', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '49eaf1403201357762d745a35882fb734107d763', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'fd25996f57a95d56bc568c89b4921edcf334b7d8', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '828fad4fd418bcdb9f5d66fec0d184c52a85ec31', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'a668fa160247d7bbe921548cb845f607b8b9305f', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'b72f0db64205d9ce462038ba995d5d31eff32dc1', 'versionType': 'git'}], 'programFiles': ['include/net/ip_fib.h'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.261', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.212', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/net/ip_fib.h'], 'defaultStatus': 'affected'}]
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 15, 2026

    Action Type Old Value New Value
    Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'a29e95fbc51e8a1b932773fd0e259b2080881443', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '5ae18d87a45698e8244d0fcba64c658c35a7dd3d', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '9127589aabdee588278e8d0d0bd3709a760a92c8', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '49eaf1403201357762d745a35882fb734107d763', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'fd25996f57a95d56bc568c89b4921edcf334b7d8', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': '828fad4fd418bcdb9f5d66fec0d184c52a85ec31', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'a668fa160247d7bbe921548cb845f607b8b9305f', 'versionType': 'git'}, {'status': 'affected', 'version': 'f4530fa574df4d833506c53697ed1daa0d390bf4', 'lessThan': 'b72f0db64205d9ce462038ba995d5d31eff32dc1', 'versionType': 'git'}], 'programFiles': ['include/net/ip_fib.h'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.6'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.6', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.261', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.212', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.178', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.97', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.40', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/net/ip_fib.h'], 'defaultStatus': 'affected'}]
    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.
    Added Reference https://git.kernel.org/stable/c/49eaf1403201357762d745a35882fb734107d763
    Added Reference https://git.kernel.org/stable/c/5ae18d87a45698e8244d0fcba64c658c35a7dd3d
    Added Reference https://git.kernel.org/stable/c/828fad4fd418bcdb9f5d66fec0d184c52a85ec31
    Added Reference https://git.kernel.org/stable/c/9127589aabdee588278e8d0d0bd3709a760a92c8
    Added Reference https://git.kernel.org/stable/c/a29e95fbc51e8a1b932773fd0e259b2080881443
    Added Reference https://git.kernel.org/stable/c/a668fa160247d7bbe921548cb845f607b8b9305f
    Added Reference https://git.kernel.org/stable/c/b72f0db64205d9ce462038ba995d5d31eff32dc1
    Added Reference https://git.kernel.org/stable/c/fd25996f57a95d56bc568c89b4921edcf334b7d8
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 10.0
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact