Linux ksmbd ACL inheritance heap corruption via malformed DACL SID
CVE-2026-8449 Published on May 12, 2026
Linux ksmbd Remote Memory Corruption via ACL Inheritance
Linux ksmbd contains a remote memory corruption vulnerability in the ACL inheritance path that allows remote clients with directory creation permissions to trigger a heap out-of-bounds read and subsequent heap corruption by setting a crafted DACL with a malformed SID containing an inflated num_subauth field. Attackers can exploit this vulnerability by creating a directory, setting the malicious DACL via SMB2_SET_INFO, and creating child entries to cause kernel instability, denial of service, or potentially achieve privilege escalation to kernel code execution.
Vulnerability Analysis
CVE-2026-8449 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
Affected Versions
Linux ksmbd:- Before and including 996454b is affected.