Critical 9.1Published Jul 25, 2026

CVE-2026-64257smb: client: reject overlapping data areas in SMB2 responses

Updated under an hour ago (Oct 27, 2026, 12:40 PM ET)

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Exploited in the last 30 days

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.

CVSS: 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: Aug 17, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 31c6312608c60b72a1feb99a5afb680645a3e8a3 before 445ece263131780dee273d727a4d6f11934feec7; 573e502d14714d2947e22e7eff40ec20a6a44a42 builds before 36bfa52459e45c0d5b668de2f1c91f6dc5c67775; 419ec1b604d7fb60c10aec2dc062371f9fcd4940 builds before 4a9d2657d3e05f6ed09c148cb127b4e58702275f; from ceb875a375dedbf51c9425c1d13a2d7a8435c08c before fdafa1e68dc75045b7b617e6e7d2854950804d83; from 6e9d10f62773b99bd927940fd9cbdfe7207e23ff before 57cba95f0e97c6f6e45e6731da30aff091bd7460; from 53b7c271f06be4dd5cfc8c6ef552a8355c891a7f before 8986c932905ea508d66da421eb2eb6e676ace1fe; 8d0bbc78046d264bbf6a574ea6f9072258a43e35; b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0; and 2 more ranges	CNA record
linux linux_kernel linux:linux_kernel	from 5.10.261 before 5.11; from 5.15.212 before 5.16; 7.2	NVD

References

References

https://git.kernel.org/stable/c/445ece263131780dee273d727a4d6f11934feec7	patch
https://git.kernel.org/stable/c/36bfa52459e45c0d5b668de2f1c91f6dc5c67775	patch
https://git.kernel.org/stable/c/4a9d2657d3e05f6ed09c148cb127b4e58702275f	patch
https://git.kernel.org/stable/c/fdafa1e68dc75045b7b617e6e7d2854950804d83	patch
https://git.kernel.org/stable/c/57cba95f0e97c6f6e45e6731da30aff091bd7460	patch
https://git.kernel.org/stable/c/8986c932905ea508d66da421eb2eb6e676ace1fe	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.