CVE-2025-38231 nfsd: Initialize ssc before laundromat_work to prevent NULL dereference
A race condition in the Linux kernel NFS server can cause a NULL pointer dereference, leading to a 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-2025-38231?
CVE-2025-38231 is a medium-severity vulnerability in Debian Debian Linux, published on 4 Jul 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:
nfsd: Initialize ssc before laundromat_work to prevent NULL dereference
In nfs4_state_start_net(), laundromat_work may access nfsd_ssc through nfs4_laundromat -> nfsd4_ssc_expire_umount. If nfsd_ssc isn't initialized, this can cause NULL pointer dereference.
Normally the delayed start of laundromat_work allows sufficient time for nfsd_ssc initialization to complete. However, when the kernel waits too long for userspace responses (e.g. in nfs4_state_start_net -> nfsd4_end_grace -> nfsd4_record_grace_done -> nfsd4_cld_grace_done -> cld_pipe_upcall -> __cld_pipe_upcall -> wait_for_completion path), the delayed work may start before nfsd_ssc initialization finishes.
Fix this by moving nfsd_ssc initialization before starting laundromat_work.
Weakness: CWE-476
Which versions are affected by CVE-2025-38231?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38231?
Apply the vendor's patch.
Is CVE-2025-38231 being exploited?
There is no known exploitation of CVE-2025-38231 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-64722, BELL-CVE-2025-38231, DEBIAN-CVE-2025-38231, GHSA-7q5j-m65f-w95r, ROOT-OS-DEBIAN-11-CVE-2025-38231, ROOT-OS-DEBIAN-12-CVE-2025-38231 and 3 more.