CVE-2025-38231: debian linux Null Dereference — Fix

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.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.10.220 — 5.10.239
linux	linux_kernel	5.14 — 5.15.186
linux	linux_kernel	5.16 — 6.1.142
linux	linux_kernel	6.2 — 6.6.95
linux	linux_kernel	6.7 — 6.12.35
linux	linux_kernel	6.13 — 6.15.4
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0fccf5f01ed28725cc313a66ca1247eef911d55e https://git.kernel.org/stable/c/5060e1a5fef184bd11d298e3f0ee920d96a23236 https://git.kernel.org/stable/c/83ac1ba8ca102ab5c0ed4351f8ac6e74ac4d5d64 https://git.kernel.org/stable/c/a97668ec6d73dab237cd1c15efe012a10090a4ed https://git.kernel.org/stable/c/b31da62889e6d610114d81dc7a6edbcaa503fcf8 https://git.kernel.org/stable/c/d622c2ee6c08147ab8c9b9e37d93b6e95d3258e0 https://git.kernel.org/stable/c/deaeb74ae9318252829c59a84a7d2316fc335660

Other References

https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html https://cert-portal.siemens.com/productcert/html/ssa-082556.html

Frequently Asked Questions

What is CVE-2025-38231? +

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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-38231? +

CVE-2025-38231 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-38231? +

CVE-2025-38231 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-38231? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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