netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto() (CVE-2026-72417) | HOL Guard CVE

Critical · CVSS 9.8CVE-2026-72417

netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto()

Answer in brief

CVE-2026-72417 records a Critical severity (CVSS 9.8) vulnerability in netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 15, 2026Updated Aug 17, 2026Source checked Sep 29, 2026First seen by HOL Aug 15, 2026Material review Aug 17, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.8
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=ab427db17885814069bae891834f20842f0ac3a4 <025a41e76b51fbc7b8eaa5bacbaa9621d00e6aa7 \|\| >=ab427db17885814069bae891834f20842f0ac3a4 <84460b644329e25809b4a6d9279d6359d7fd8ebc	025a41e76b51fbc7b8eaa5bacbaa9621d00e6aa7, 84460b644329e25809b4a6d9279d6359d7fd8ebc
Linux/Linuxgeneric	6.19	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 025a41e76b51fbc7b8eaa5bacbaa9621d00e6aa7 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 15, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 15, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto() Add sanity check for iph->ihl field in nf_flow_ip4_tunnel_proto() before using it to compute the header size, avoiding out-of-bounds access with malformed IP headers. While at it, use iph->protocol instead of the hardcoded IPPROTO_IPIP constant when setting ctx->tun.proto and reference ctx->tun.hdr_size when updating ctx->offset.

Quoted source text, attributed separately from HOL analysis.