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CVE-2026-64385: smb: client: fix double-free in SMB2_ioctl() replay

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-25 · updated 2026-10-19
• Weakness: CWE-415

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-free in SMB2_ioctl() replay A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_ioctl_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.

Affected products

• Linux kernel: from 6.6.32 before 6.6.145; from 6.8.1 before 6.12.96; from 6.13 before 6.18.39; from 6.19 before 7.1.4; 6.8, 6.8-rc2, 6.8-rc3, 6.8-rc4, 6.8-rc5, 6.8-rc6 (+1) — fixed in 6.12.96, 6.18.39, 6.6.145, 7.1.4

How to fix

Upgrade to a fixed version: Linux kernel 6.12.96, 6.18.39, 6.6.145, 7.1.4. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0be4bc64882edaefaaee8d1e27d083643eb778e6
• https://git.kernel.org/stable/c/276c8efbc49f9303ac76d0d4deab7128581b0f3b
• https://git.kernel.org/stable/c/96fcfc8ae7359346156e492ca610e830d2649ad6
• https://git.kernel.org/stable/c/f9bbadb6c94583e3b4af1afc449bfceb1d1ddec9
• https://git.kernel.org/stable/c/fc65ffb4ef1bf540da16b17c225ae51091e07d72

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