CVE-2023-53998 hwrng: virtio - Fix race on data_avail and actual data
A race condition in the Linux kernel virtio RNG driver allows attackers to read stale entropy data or cause service disruption.
- 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-2023-53998?
CVE-2023-53998 is a vulnerability in Linux, published on 24 Dec 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:
hwrng: virtio - Fix race on data_avail and actual data
The virtio rng device kicks off a new entropy request whenever the data available reaches zero. When a new request occurs at the end of a read operation, that is, when the result of that request is only needed by the next reader, then there is a race between the writing of the new data and the next reader.
This is because there is no synchronisation whatsoever between the writer and the reader.
Fix this by writing data_avail with smp_store_release and reading it with smp_load_acquire when we first enter read. The subsequent reads are safe because they're either protected by the first load acquire, or by the completion mechanism.
Also remove the redundant zeroing of data_idx in random_recv_done (data_idx must already be zero at this point) and data_avail in request_entropy (ditto).
Which versions are affected by CVE-2023-53998?
How do I fix CVE-2023-53998?
Apply the vendor's patch.
Is CVE-2023-53998 being exploited?
There is no known exploitation of CVE-2023-53998 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2023-53998, DEBIAN-CVE-2023-53998, GHSA-g2vv-m9x5-457j, UBUNTU-CVE-2023-53998.