CVE-2026-52936 crypto: jitterentropy - replace long-held spinlock with mutex
Parallel readers can cause system stalls by spinning on a long-held spinlock during entropy generation, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52936?
CVE-2026-52936 is a medium-severity denial of service vulnerability in Linux kernel, published on 24 Jun 2026. 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:
crypto: jitterentropy - replace long-held spinlock with mutex
jent_kcapi_random() serializes the shared jitterentropy state, but it currently holds a spinlock across the jent_read_entropy() call. That path performs expensive jitter collection and SHA3 conditioning, so parallel readers can trigger stalls as contending waiters spin for the same lock.
To prevent non-preemptible lock hold, replace rng->jent_lock with a mutex so contended readers sleep instead of spinning on a shared lock held across expensive entropy generation.
Which versions are affected by CVE-2026-52936?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-52936?
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-2026-52936 being exploited?
There is no known exploitation of CVE-2026-52936 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-52936, DEBIAN-CVE-2026-52936, GHSA-9hmp-j3gc-jm6j, ROOT-OS-DEBIAN-11-CVE-2026-52936, ROOT-OS-DEBIAN-12-CVE-2026-52936, ROOT-OS-UBUNTU-2204-CVE-2026-52936 and 2 more.