Bug 2407085 (CVE-2025-40084)

Summary: CVE-2025-40084 kernel: ksmbd: transport_ipc: validate payload size before reading handle
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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OS: Linux   
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Description OSIDB Bzimport 2025-10-29 14:03:05 UTC 
In the Linux kernel, the following vulnerability has been resolved:

ksmbd: transport_ipc: validate payload size before reading handle

handle_response() dereferences the payload as a 4-byte handle without
verifying that the declared payload size is at least 4 bytes. A malformed
or truncated message from ksmbd.mountd can lead to a 4-byte read past the
declared payload size. Validate the size before dereferencing.

This is a minimal fix to guard the initial handle read.
Comment 1 Jon Moroney 2025-10-29 17:39:32 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025102909-CVE-2025-40084-1407@gregkh/T