netfilter: nft_lookup: fix catchall element handling with inverted lookups (CVE-2026-72320) | HOL Guard CVE

Critical · CVSS 9.1CVE-2026-72320

netfilter: nft_lookup: fix catchall element handling with inverted lookups

Answer in brief

CVE-2026-72320 records a Critical severity (CVSS 9.1) vulnerability in netfilter: nft_lookup: fix catchall element handling with inverted lookups. 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 9.1
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 9.1. 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	>=aaa31047a6d25da0fa101da1ed544e1247949b40 <0ab8880865f9678eb6174e72c1fc4712e44c745c \|\| >=aaa31047a6d25da0fa101da1ed544e1247949b40 <238c612357b5a25f03eacf356f95034f8551f218 \|\| >=aaa31047a6d25da0fa101da1ed544e1247949b40 <ef0c7d4b04a0e6ad175323c24bc84e11470dd79d \|\| >=aaa31047a6d25da0fa101da1ed544e1247949b40 <e6107a4c74b54cb33e3bce162a63048ae5a6b198	0ab8880865f9678eb6174e72c1fc4712e44c745c, 238c612357b5a25f03eacf356f95034f8551f218, ef0c7d4b04a0e6ad175323c24bc84e11470dd79d, e6107a4c74b54cb33e3bce162a63048ae5a6b198
Linux/Linuxgeneric	5.13	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 0ab8880865f9678eb6174e72c1fc4712e44c745c 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: nft_lookup: fix catchall element handling with inverted lookups nft_lookup_eval() decides whether a lookup matched (`found`) from the direct set lookup and priv->invert before falling back to the catchall element used by interval sets (e.g. nft_set_rbtree) for the open-ended default range. Since `found` is never recomputed after `ext` is replaced by the catchall lookup, inverted lookups (NFT_LOOKUP_F_INV, "!= @set") can wrongly match or wrongly skip the catchall element, producing the wrong verdict. Fold the catchall lookup into `ext` before computing `found`, matching the order already used by nft_objref_map_eval().

Quoted source text, attributed separately from HOL analysis.