CVE-2023-52925 netfilter: nf_tables: don't fail inserts if duplicate has expired
A logic error in Linux kernel nftables causes insertion failures for expired duplicate entries, potentially leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2023-52925?
CVE-2023-52925 is a medium-severity denial of service vulnerability in Linux kernel, published on 5 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2023-52925?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2023-52925?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2023-52925 being exploited?
There is no known exploitation of CVE-2023-52925 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2023-52925, GHSA-cgvr-gqfv-x5mj, UBUNTU-CVE-2023-52925.