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).
References5
- git.kernel.org/stable/c/1dac61e2c29d1a71784604b48cf3b1234a65ec29
- git.kernel.org/stable/c/596b4062e6c75bdd85a7f2b7f2087a872dc420ac
- git.kernel.org/stable/c/68652afb9b9adf70125971abee9b95341e042249
- git.kernel.org/stable/c/9312a00215602ba028495ef3fa00fb84af0478e0
- git.kernel.org/stable/c/d96f3365ce61c5f39602955af43c8174548dee98
Metrics
- CVSS 3.1
-
7.0
HIGH
Score source: CNA
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 3 · as of 3 November 2026
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