CVE-2026-64257

Critical

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject overlapping data areas in SMB2 responses Commit 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") restricted the implied bcc[0] length exception to responses without a data area. However, the overlap handling in __smb2_calc_size() clears data_length, which can make an invalid response appear to have no data area and so qualify for the exception. Track data area overlap separately and reject such responses before applying the length compatibility exceptions.

SeverityCritical
CVSS9.1
Exploit probability—
ProductLinux Kernel
PublishedJul 25, 2026
First seenJul 25, 2026

How to fix

Update
  • linux linux_kernel5.11, 5.16 or later

Affected products

ProductAffected versionsFixed in
linux linux_kernel5.10.261 ≤ v < 5.11, 5.15.212 ≤ v < 5.16, 7.25.11, 5.16

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