CVE-2026-72421

CRITICALPre-NVD 10.010.0—
EchelonGraph scoreHIGH confidence

Score 10.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-15. a secondary CVSS source baseline 10.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 5 sources updated this week
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 10.0Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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

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.

CVSS v3
10.0
EG Score
10.0(high)
EG Risk
50(Track)
EG Risk 50/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity100% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
44%
KEV
Not listed

Published

August 15, 2026

Last Modified

August 17, 2026

Advisory Details (8)

Auto-updated Aug 17, 2026
No patch confirmed yet.
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/fd25996f57a95d56bc568c89b4921edcf334b7d8
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/b72f0db64205d9ce462038ba995d5d31eff32dc1
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a668fa160247d7bbe921548cb845f607b8b9305f
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/a29e95fbc51e8a1b932773fd0e259b2080881443
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/9127589aabdee588278e8d0d0bd3709a760a92c8
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/828fad4fd418bcdb9f5d66fec0d184c52a85ec31
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5ae18d87a45698e8244d0fcba64c658c35a7dd3d
generic

ipv4: fib: Don't ignore error route in local/main tables. - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/49eaf1403201357762d745a35882fb734107d763

Vendor Advisories for CVE-2026-72421(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Data Freshness Timeline

(refreshed 52× in last 7d / 52× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-21 08:21 UTCGHSA enrichment
  2. 2026-08-21 04:44 UTCGHSA enrichment
  3. 2026-08-21 01:07 UTCEG score recompute
  4. 2026-08-21 01:07 UTCGHSA enrichment
  5. 2026-08-20 22:56 UTCEPSS rescore
  6. 2026-08-20 21:30 UTCGHSA enrichment
  7. 2026-08-20 17:53 UTCGHSA enrichment
  8. 2026-08-20 14:16 UTCGHSA enrichment
  9. 2026-08-20 10:36 UTCGHSA enrichment
  10. 2026-08-20 06:59 UTCGHSA enrichment
  11. 2026-08-20 03:23 UTCGHSA enrichment
  12. 2026-08-19 23:46 UTCGHSA enrichment
  13. 2026-08-19 20:08 UTCEG score recompute
  14. 2026-08-19 20:08 UTCGHSA enrichment
  15. 2026-08-19 17:04 UTCEPSS rescore
  16. 2026-08-19 16:30 UTCGHSA enrichment
  17. 2026-08-19 12:53 UTCGHSA enrichment
  18. 2026-08-19 09:16 UTCGHSA enrichment
  19. 2026-08-19 05:39 UTCGHSA enrichment
  20. 2026-08-19 02:02 UTCGHSA enrichment
  21. 2026-08-18 22:24 UTCGHSA enrichment
  22. 2026-08-18 18:48 UTCGHSA enrichment
  23. 2026-08-18 15:11 UTCEG score recompute
  24. 2026-08-18 15:11 UTCGHSA enrichment
  25. 2026-08-18 13:49 UTCEPSS rescore
Show 27 more
  1. 2026-08-18 13:49 UTCEPSS rescore
  2. 2026-08-18 11:31 UTCGHSA enrichment
  3. 2026-08-18 07:53 UTCGHSA enrichment
  4. 2026-08-18 04:16 UTCGHSA enrichment
  5. 2026-08-18 00:37 UTCGHSA enrichment
  6. 2026-08-17 20:58 UTCGHSA enrichment
  7. 2026-08-17 17:21 UTCEG score recompute
  8. 2026-08-17 17:21 UTCGHSA enrichment
  9. 2026-08-17 13:47 UTCEPSS rescore
  10. 2026-08-17 13:42 UTCGHSA enrichment
  11. 2026-08-17 10:05 UTCEG score recompute
  12. 2026-08-17 10:05 UTCGHSA enrichment
  13. 2026-08-17 06:28 UTCEG score recompute
  14. 2026-08-17 06:28 UTCGHSA enrichment
  15. 2026-08-17 05:57 UTCEG score recompute▲ 10.00
  16. 2026-08-17 05:57 UTCGHSA enrichment
  17. 2026-08-17 05:54 UTCMITRE cvelistV5CVSS v3 → 10 · severity → CRITICAL
  18. 2026-08-17 05:29 UTCEG score recompute
  19. 2026-08-17 05:29 UTCGHSA enrichment
  20. 2026-08-17 05:24 UTCMITRE cvelistV5
  21. 2026-08-16 14:56 UTCEPSS rescore
  22. 2026-08-16 14:56 UTCEPSS rescore
  23. 2026-08-16 02:15 UTCEPSS rescore
  24. 2026-08-15 06:34 UTCGHSA enrichment
  25. 2026-08-15 06:23 UTCNVD update
  26. 2026-08-15 06:04 UTCEG score recompute
  27. 2026-08-15 06:02 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-72421?
CVE-2026-72421 is a critical vulnerability published on August 15, 2026. In the Linux kernel, the following vulnerability has been resolved: ipv4: fib: Don't ignore error route in local/main tables. When CONFIGIPMULTIPLE_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,…
When was CVE-2026-72421 disclosed?
CVE-2026-72421 was first published in the National Vulnerability Database on August 15, 2026, with the most recent update on August 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-72421 actively exploited?
CVE-2026-72421 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 56.0% of all scored CVEs.
What is the CVSS score of CVE-2026-72421?
CVE-2026-72421 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2026-72421?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-72421, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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