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CVE-2026-72320: netfilter: nft_lookup: fix catchall element handling with inverted lookups

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-15 · updated 2026-10-30

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().

Affected products

• Linux: 5.13 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0ab8880865f9678eb6174e72c1fc4712e44c745c
• https://git.kernel.org/stable/c/238c612357b5a25f03eacf356f95034f8551f218
• https://git.kernel.org/stable/c/65d35cb555f40529a9edc6bf4beaa3bee917f015
• https://git.kernel.org/stable/c/87ff022a58788ff4a25cf2c609b9abae418c9323
• https://git.kernel.org/stable/c/e6107a4c74b54cb33e3bce162a63048ae5a6b198
• https://git.kernel.org/stable/c/ef0c7d4b04a0e6ad175323c24bc84e11470dd79d

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