What’s Vulnerable › Vulnerabilities

CVE-2023-3866: ksmbd: validate session id and tree id in the compound request

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 12.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-08-16 · updated 2026-08-04
• Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate session id and tree id in the compound request This patch validate session id and tree id in compound request. If first operation in the compound is SMB2 ECHO request, ksmbd bypass session and tree validation. So work->sess and work->tcon could be NULL. If secound request in the compound access work->sess or tcon, It cause NULL pointer dereferecing error.

Affected products

• Linux kernel: from 5.15 before 5.15.121; from 5.16 before 6.1.36; from 6.2 before 6.3.10; 6.4-rc1, 6.4-rc2, 6.4-rc3, 6.4-rc4, 6.4-rc5, 6.4-rc6 (+1) — fixed in 5.15.121, 6.1.36, 6.3.10

How to fix

Upgrade to a fixed version: Linux kernel 5.15.121, 6.1.36, 6.3.10. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/5005bcb4219156f1bf7587b185080ec1da08518e
• https://git.kernel.org/stable/c/854156d12caa9d36de1cf5f084591c7686cc8a9d
• https://git.kernel.org/stable/c/d1066c1b3663401cd23c0d6e60cdae750ce00c0f
• https://git.kernel.org/stable/c/eb947403518ea3d93f6d89264bb1f5416bb0c7d0

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