EUVD-2026-24640
GHSA-f75p-6q8j-p2f2
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
7DescriptionNVD
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix OOB write in QUERY_INFO for compound requests
When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor.
The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs.
This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning.
AnalysisAI
Out-of-bounds write in Linux kernel's ksmbd server allows authenticated remote attackers with low-privilege SMB access to corrupt memory and potentially execute arbitrary code or crash the system. The vulnerability triggers when processing compound SMB2 requests (e.g., READ + QUERY_INFO for security descriptors) where the first command consumes most of the response buffer, causing ksmbd to write beyond allocated memory when building security descriptors from POSIX ACLs. …
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RemediationAI
Within 24 hours: identify all Linux systems running ksmbd with kernel versions prior to 6.12.81, 6.18.22, 6.19.12, or 7.0 using kernel enumeration or asset inventory tools. Within 7 days: apply vendor-released patches to affected systems (kernel 6.12.81+, 6.18.22+, 6.19.12+, or 7.0+) and validate via reboot testing in non-production environments. …
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