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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于SMB2响应中重叠数据区域处理不当，可能使无效响应被错误接受，导致安全风险。

CVSS 9.1 · Critical EPSS 0.70% · P52

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 11

VendorProduct Version RangeStatus
Linux Linux 31c6312608c60b72a1feb99a5afb680645a3e8a3< 445ece263131780dee273d727a4d6f11934feec7 affected
573e502d14714d2947e22e7eff40ec20a6a44a42< 36bfa52459e45c0d5b668de2f1c91f6dc5c67775 affected
419ec1b604d7fb60c10aec2dc062371f9fcd4940< 4a9d2657d3e05f6ed09c148cb127b4e58702275f affected
ceb875a375dedbf51c9425c1d13a2d7a8435c08c< fdafa1e68dc75045b7b617e6e7d2854950804d83 affected
6e9d10f62773b99bd927940fd9cbdfe7207e23ff< 57cba95f0e97c6f6e45e6731da30aff091bd7460 affected
53b7c271f06be4dd5cfc8c6ef552a8355c891a7f< 8986c932905ea508d66da421eb2eb6e676ace1fe affected
8d0bbc78046d264bbf6a574ea6f9072258a43e35 affected
b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0 affected
… +3 more rows
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I. Basic Information for CVE-2026-64257

Vulnerability Information
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Vulnerability Title
smb: client: reject overlapping data areas in SMB2 responses
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于SMB2响应中重叠数据区域处理不当，可能使无效响应被错误接受，导致安全风险。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 31c6312608c60b72a1feb99a5afb680645a3e8a3 ~ 445ece263131780dee273d727a4d6f11934feec7 -
Linux Linux - -

II. Public POCs for CVE-2026-64257

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III. Intelligence Information for CVE-2026-64257

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Patches & Fixes for CVE-2026-64257 (5)

Same Patch Batch · Linux · 2026-07-25 · 274 CVEs total

CVE-2026-64355 9.8 CRITICAL bpf: Reject fragmented frames in devmap
CVE-2026-64459 9.8 CRITICAL tcp: restore RCU grace period in tcp_ao_destroy_sock
CVE-2026-64303 9.8 CRITICAL spi: fsl-lpspi: terminate the RX channel on TX prepare failure path
CVE-2026-64439 9.8 CRITICAL crypto: krb5 - filter out async aead implementations at alloc
CVE-2026-64410 9.8 CRITICAL netfilter: flowtable: IPIP tunnel hardware offload is not yet support
CVE-2026-64399 9.8 CRITICAL ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE
CVE-2026-64397 9.8 CRITICAL ksmbd: serialize QUERY_DIRECTORY requests per file
CVE-2026-64391 9.8 CRITICAL ksmbd: use opener credentials for ADS I/O
CVE-2026-64387 9.8 CRITICAL smb: client: fix query directory replay double-free
CVE-2026-64386 9.8 CRITICAL smb: client: fix query_info() replay double-free
CVE-2026-64385 9.8 CRITICAL smb: client: fix double-free in SMB2_ioctl() replay
CVE-2026-64383 9.8 CRITICAL smb: client: fix double-free in SMB2_flush() replay
CVE-2026-64384 9.8 CRITICAL smb: client: fix change notify replay double-free
CVE-2026-64268 9.8 CRITICAL RDMA/siw: bound Read Response placement to the RREAD length
CVE-2026-64523 9.8 CRITICAL net/handshake: Take a long-lived file reference at submit
CVE-2026-64450 9.1 CRITICAL tipc: fix out-of-bounds read in broadcast Gap ACK blocks
CVE-2026-64392 9.1 CRITICAL ksmbd: use opener credentials for delete-on-close
CVE-2026-64393 9.1 CRITICAL ksmbd: run set info with opener credentials
CVE-2026-64269 9.1 CRITICAL RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg
CVE-2026-64320 9.1 CRITICAL nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page

Showing top 20 of 274 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64257

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