CVE-2025-39975
A critical bug in the Linux kernel’s SMB client can let attackers read or write arbitrary memory by exploiting an indexing error in the smb2_compound_op() function. The flaw can cause crashes or allow attackers to run arbitrary code. A patch has been released to fix the issue.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel versions that include the SMB client before the patch, across all distributions that use the default kernel SMB client.
Real-world impact
An attacker could send specially crafted SMB requests to a vulnerable system, causing a denial of service or executing arbitrary code, potentially taking full control of the machine.
Why this severity
The CVSS score of 9.8 reflects that the vulnerability is exploitable remotely without authentication or user interaction, and it can compromise confidentiality, integrity, and availability of the affected system.
What to do about it
- 01Upgrade your Linux kernel to a version that includes the fix for CVE-2025-39975.
- 02Reboot the system to load the new kernel.
NVD description indicates fix
Timeline
- Oct 15, 2025 · Oct 15, 2025PublishedDisclosed and added to the National Vulnerability Database.
- Jul 30, 2026 · 6d agoAdvisory updatedThe NVD record was last revised.
- Jul 30, 2026 · 6d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.