CVE-2026-99110
Received
Received - Intake
Heap Overflow in Linux Kernel SMB Client
Vulnerability report for CVE-2026-99110, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-28
Last updated on: 2026-10-28
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix heap overflow in cifs_do_set_acl()
cifs_set_acl() validates ACL size using posix_acl_xattr_size():
4 + (count * 8) // 4-byte header + 8 bytes per ACE
cifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS
wire format into the same buffer:
6 + (count * 10) // 6-byte header + 10 bytes per ACE
An ACL that passes the xattr-based check in cifs_set_acl() can
overflow the heap when posix_acl_to_cifs() writes the larger CIFS
format.
Validate the CIFS format size against the remaining buffer space and
USHRT_MAX before converting--data_count is __u16, so sizes above
USHRT_MAX truncate the on-wire packet length, causing the server to
apply a partial ACL. Replace MaxDataCount = 1000 with
min(CIFSMaxBufSize, USHRT_MAX).
CVSS Scores
EPSS Scores
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Meta Information
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
