Bug 2507108 (CVE-2026-64381)

Summary: CVE-2026-64381 kernel: smb: client: Fix next buffer leak in receive_encrypted_standard()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the SMB client of the Linux kernel. A remote attacker could exploit a memory leak in the `receive_encrypted_standard()` function by sending specially crafted compound Protocol Data Units (PDUs). This vulnerability occurs because a buffer is allocated before a necessary size check, leading to the buffer not being freed if the check fails. Repeated exploitation of this flaw could lead to a Denial of Service (DoS) due to memory exhaustion.
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Description OSIDB Bzimport 2026-07-25 10:05:23 UTC 
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.
Comment 1 TEJ RATHI 2026-07-30 05:20:36 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072525-CVE-2026-64381-5b4a@gregkh/T