CVE-2023-52925: netfilter: nf_tables: don't fail inserts if duplicate has expired

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-02-05 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: don't fail inserts if duplicate has expired nftables selftests fail: run-tests.sh testcases/sets/0044interval_overlap_0 Expected: 0-2 . 0-3, got: W: [FAILED] ./testcases/sets/0044interval_overlap_0: got 1 Insertion must ignore duplicate but expired entries. Moreover, there is a strange asymmetry in nft_pipapo_activate: It refetches the current element, whereas the other ->activate callbacks (bitmap, hash, rhash, rbtree) use elem->priv. Same for .remove: other set implementations take elem->priv, nft_pipapo_remove fetches elem->priv, then does a relookup, remove this. I suspect this was the reason for the change that prompted the removal of the expired check in pipapo_get() in the first place, but skipping exired elements there makes no sense to me, this helper is used for normal get requests, insertions (duplicate check) and deactivate callback. In first two cases expired elements must be skipped. For ->deactivate(), this gets called for DELSETELEM, so it seems to me that expired elements should be skipped as well, i.e. delete request should fail with -ENOENT error.

Affected products

Linux kernel: from 4.19.316 before 4.20; from 5.4.262 before 5.5; 6.4.11, 6.5-rc6 — fixed in 4.20, 5.5

How to fix

Upgrade to a fixed version: Linux kernel 4.20, 5.5. Check the vendor advisory for mitigations.

References

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