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

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-25 · updated 2026-09-08
• Weakness: CWE-787

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.

Affected products

• Linux kernel: from 4.19 before 5.10.261; from 5.11 before 5.15.212; from 5.16 before 6.1.178; from 6.2 before 6.6.145; from 6.7 before 6.12.96; from 6.13 before 6.18.39 — fixed in 5.10.261, 5.15.212, 6.1.178, 6.12.96, 6.18.39, 6.6.145

How to fix

Upgrade to a fixed version: Linux kernel 5.10.261, 5.15.212, 6.1.178, 6.12.96. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/07e0ab81df1790afa35732a4e8e07ff831b29008
• https://git.kernel.org/stable/c/1c6267a1d5cf4c73b656f8181b310cbbb3e4767b
• https://git.kernel.org/stable/c/297243e365fc9fe2f8e9b7dd535a65d922cd108b
• https://git.kernel.org/stable/c/67097772df7791c53d608f04bd31c676ccf79b83
• https://git.kernel.org/stable/c/68fc0b6cc03ca58060c0f36454e169f5fe258974
• https://git.kernel.org/stable/c/9136a08dc29328edd9867f2545e73906ac9df93b
• https://git.kernel.org/stable/c/927d4805aea0a287d36dd4f826ee24d69a2afee3
• https://git.kernel.org/stable/c/94e4f672db029414b9888b5137a7559f1febf2d8

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