CVE-2026-64257

smb: client: reject overlapping data areas in SMB2 responses

CRITICAL
9.1
CVSS Score
Published: July 25, 2026 at 08:49 AM UTC
Updated: August 17, 2026 at 05:17 AM UTC
1 product affected across 1 vendorLinux Kernel

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Severity
CRITICAL9.1
Exploit prediction
EPSS 0.7%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≥ 5.10.261v ≥ 5.15.2125.10.261 ≤ v < 5.115.15.212 ≤ v < 5.1631c6312608c60b72a1feb99a5afb680645a3e8a3419ec1b604d7fb60c10aec2dc062371f9fcd49405.10.2615.15.21253b7c271f06be4dd5cfc8c6ef552a8355c891a7f573e502d14714d2947e22e7eff40ec20a6a44a426e9d10f62773b99bd927940fd9cbdfe7207e23ff7.2 rc38d0bbc78046d264bbf6a574ea6f9072258a43e35b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0ceb875a375dedbf51c9425c1d13a2d7a8435c08c
Vendor states this is fixed in 36bfa52459e45c0d5b668de2f1c91f6dc5c67775 (fixed)
Vendor states this is fixed in 445ece263131780dee273d727a4d6f11934feec7 (fixed)
Vendor states this is fixed in 4a9d2657d3e05f6ed09c148cb127b4e58702275f (fixed)
Vendor states this is fixed in 57cba95f0e97c6f6e45e6731da30aff091bd7460 (fixed)
Vendor states this is fixed in 8986c932905ea508d66da421eb2eb6e676ace1fe (fixed)
Vendor states this is fixed in fdafa1e68dc75045b7b617e6e7d2854950804d83 (fixed)
Affected range stops below 5.11, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.16, so it looks safe — our inference, not a vendor statement

CVSS

9.1CRITICALLinux
Vector?

Quick Info

StatusANALYZED
CWE
NVD-CWE-noinfo

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