SB2026091666 - NULL pointer dereference in Linux kernel nfsd

Description

This security bulletin contains information about 1 vulnerability.

1) NULL pointer dereference (CVE-ID: CVE-2026-90039)

CWE-ID: CWE-476 - NULL Pointer Dereference

CVSSv4: 6.7 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local privileged user to cause a denial of service.

The vulnerability exists due to a null pointer dereference in NFSD NFSv4 state-revocation and asynchronous COPY walkers when processing unlock filesystem or export operations before NFSD startup completes. A local privileged user can write to the unlock filesystem interface or send an NFSD unlock netlink command to cause a denial of service.

The condition occurs when an NFSD listener has been created but no NFSD thread has started.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/0146467a2fce845cb6629979c3e9c58dd3d3a6a3
• https://git.kernel.org/stable/c/104a51265042b4424085741c963cb858ac29ec0b
• https://git.kernel.org/stable/c/2f3e6638aebc0ab8afb8b4e9816ea9a1cad85378