CVE-2026-72320
CriticalCVSS 9.1Exploitation Probability (EPSS)
Low risk11th percentile - higher than 11% of all known CVEs
Summary
In the Linux kernel, the netfilter nft_lookup module has a bug in catchall element handling with inverted lookups. The 'found' variable is not recomputed after 'ext' is replaced by the catchall lookup, which can lead to incorrect matching or skipping of the catchall element in negated queries.
Risk Assessment
Incorrect packet filtering decisions may allow unauthorized traffic or block legitimate traffic, violating network security policy.
Recommendation
Apply the Linux kernel update containing the fix for this vulnerability. If possible, restrict the use of inverted lookups in nftables rules until the update is applied.
Original NVD description (English source)
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().