CVE-2026-72417: Linux kernel · netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 7.0.0-1013.13~24.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 45% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 7.0.0-1013.13~24.04.1, 7.0.0-1017.17~24.04.1, 7.0.0-1016.16~24.04.1 +12
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and included in the Linux kernel security update referenced by Ubuntu Security Notice USN-8816-1. Users should apply the update and reboot their systems. Due to an ABI change, recompilation and reinstallation of third-party kernel modules are required. Follow vendor instructions for updating to the fixed kernel versions to fully remediate this vulnerability.
Description
A vulnerability in the Linux kernel's netfilter flowtable subsystem was fixed by adding a sanity check for the IP header length field (iph->ihl) in the nf_flow_ip4_tunnel_proto() function. This prevents out-of-bounds memory access caused by malformed IP headers. The fix also improved protocol handling by using the actual protocol field instead of a hardcoded constant. The vulnerability affects multiple Linux kernel versions and was addressed in a security update requiring a system reboot and recompilation of third-party kernel modules.
References
- nvd.nist.gov/vuln/detail/CVE-2026-72417 (opens in a new tab)
- git.kernel.org/stable/c/025a41e76b51fbc7b8eaa5bacbaa9621d00e6aa7 (opens in a new tab)
- git.kernel.org/stable/c/84460b644329e25809b4a6d9279d6359d7fd8ebc (opens in a new tab)
- ubuntu.com/security/CVE-2026-72417 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-72417 (opens in a new tab)
- git.kernel.org/linus/84460b644329e25809b4a6d9279d6359d7fd8ebc (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8816-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-2 (opens in a new tab)