FKIE_CVE-2026-72421
Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-10-16 19:17
Severity
Summary
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"include/net/ip_fib.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "a29e95fbc51e8a1b932773fd0e259b2080881443",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
},
{
"lessThan": "5ae18d87a45698e8244d0fcba64c658c35a7dd3d",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
},
{
"lessThan": "9127589aabdee588278e8d0d0bd3709a760a92c8",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
},
{
"lessThan": "49eaf1403201357762d745a35882fb734107d763",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
},
{
"lessThan": "fd25996f57a95d56bc568c89b4921edcf334b7d8",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
},
{
"lessThan": "828fad4fd418bcdb9f5d66fec0d184c52a85ec31",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
},
{
"lessThan": "a668fa160247d7bbe921548cb845f607b8b9305f",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
},
{
"lessThan": "b72f0db64205d9ce462038ba995d5d31eff32dc1",
"status": "affected",
"version": "f4530fa574df4d833506c53697ed1daa0d390bf4",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"include/net/ip_fib.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.6"
},
{
"lessThan": "3.6",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: fib: Don\u0027t ignore error route in local/main tables.\n\nWhen CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added,\nfib_lookup() performs route lookup directly on two tables.\n\nSince the first lookup does not properly bail out, the result\nof an error route in the merged local/main table could be\noverwritten by another route in the default table:\n\n # unshare -n\n # ip link set lo up\n # ip route add 192.168.0.0/24 dev lo table 253\n # ip route add unreachable 192.168.0.0/24\n # ip route get 192.168.0.1\n 192.168.0.1 dev lo table default uid 0\n cache \u003clocal\u003e\n\nOnce a random rule is added, the error route is respected:\n\n # ip rule add table 0\n # ip rule del table 0\n # ip route get 192.168.0.1\n RTNETLINK answers: No route to host\n\nLet\u0027s fix the inconsistent behaviour."
}
],
"id": "CVE-2026-72421",
"lastModified": "2026-10-16T19:17:29.613",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 10.0,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.8,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-72421",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T18:49:34.990573Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-08-15T06:22:15.867",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/49eaf1403201357762d745a35882fb734107d763"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/5ae18d87a45698e8244d0fcba64c658c35a7dd3d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/828fad4fd418bcdb9f5d66fec0d184c52a85ec31"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/9127589aabdee588278e8d0d0bd3709a760a92c8"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a29e95fbc51e8a1b932773fd0e259b2080881443"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a668fa160247d7bbe921548cb845f607b8b9305f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b72f0db64205d9ce462038ba995d5d31eff32dc1"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/fd25996f57a95d56bc568c89b4921edcf334b7d8"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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