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CVE-2026-64381— smb: client: Fix next buffer leak in receive_encrypted_standard()

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 4.19版本存在安全漏洞，该漏洞源于receive_encrypted_standard()在分配next_buffer前未检查MAX_COMPOUND，可能导致缓冲区泄漏。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.18% · P7

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux b24df3e30cbf48255db866720fb71f14bf9d2f39< 94e4f672db029414b9888b5137a7559f1febf2d8 affected
b24df3e30cbf48255db866720fb71f14bf9d2f39< 68fc0b6cc03ca58060c0f36454e169f5fe258974 affected
b24df3e30cbf48255db866720fb71f14bf9d2f39< 07e0ab81df1790afa35732a4e8e07ff831b29008 affected
b24df3e30cbf48255db866720fb71f14bf9d2f39< 9136a08dc29328edd9867f2545e73906ac9df93b affected
b24df3e30cbf48255db866720fb71f14bf9d2f39< 67097772df7791c53d608f04bd31c676ccf79b83 affected
b24df3e30cbf48255db866720fb71f14bf9d2f39< 297243e365fc9fe2f8e9b7dd535a65d922cd108b affected
b24df3e30cbf48255db866720fb71f14bf9d2f39< 927d4805aea0a287d36dd4f826ee24d69a2afee3 affected
b24df3e30cbf48255db866720fb71f14bf9d2f39< 1c6267a1d5cf4c73b656f8181b310cbbb3e4767b affected
… +10 more rows
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I. Basic Information for CVE-2026-64381

Vulnerability Information
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Vulnerability Title
smb: client: Fix next buffer leak in receive_encrypted_standard()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: Fix next buffer leak in receive_encrypted_standard() receive_encrypted_standard() allocates next_buffer before checking whether the number of compound PDUs already reached MAX_COMPOUND. If the limit check fails, the function returns immediately and the newly allocated next_buffer is not assigned to server->smallbuf/server->bigbuf, making it leaked. Move the MAX_COMPOUND check before allocating next_buffer.
Source: CVE Program / CVE List V5
CVSS Information
N/A
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 4.19版本存在安全漏洞，该漏洞源于receive_encrypted_standard()在分配next_buffer前未检查MAX_COMPOUND，可能导致缓冲区泄漏。
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 b24df3e30cbf48255db866720fb71f14bf9d2f39 ~ 94e4f672db029414b9888b5137a7559f1febf2d8 -
Linux Linux 4.19 -

II. Public POCs for CVE-2026-64381

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III. Intelligence Information for CVE-2026-64381

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Patches & Fixes for CVE-2026-64381 (8)

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-2026-64269 9.1 CRITICAL RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg
CVE-2026-64257 9.1 CRITICAL smb: client: reject overlapping data areas in SMB2 responses
CVE-2026-64319 9.1 CRITICAL nvmet-auth: validate reply message payload bounds against transfer length
CVE-2026-64320 9.1 CRITICAL nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page
CVE-2026-64393 9.1 CRITICAL ksmbd: run set info with opener credentials

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-2026-64381

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