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CVE PROGRAM SOURCE RECORD8.8 High

CVE-2026-31709

smb: client: validate the whole DACL before rewriting it in cifsacl

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: validate the whole DACL before rewriting it in cifsacl build_sec_desc() and id_mode_to_cifs_acl() derive a DACL pointer from a server-supplied dacloffset and then use the incoming ACL to rebuild the chmod/chown security descriptor. The original fix only checked that the struct smb_acl header fits before reading dacl_ptr->size or dacl_ptr->num_aces. That avoids the immediate header-field OOB read, but the rewrite helpers still walk ACEs based on pdacl->num_aces with no structural validation of the incoming DACL body. A malicious server can return a truncated DACL that still contains a header, claims one or more ACEs, and then drive replace_sids_and_copy_aces() or set_chmod_dacl() past the validated extent while they compare or copy attacker-controlled ACEs. Factor the DACL structural checks into validate_dacl(), extend them to validate each ACE against the DACL bounds, and use the shared validator before the chmod/chown rebuild paths. parse_dacl() reuses the same validator so the read-side parser and write-side rewrite paths agree on what constitutes a well-formed incoming DACL.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 to < b8603d9ae6c9087662b098619996bc4a8064319daffected
  • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 to < c2abdebf72000a64603ced84d36ccbd164f11391affected
  • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 to < 8e47d297e7cf9a6029a0d38e7b22faba7d7aaf12affected
  • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 to < d92f3f0b22414e7515696a02224d0af55e3004a3affected
  • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 to < ff0ca46b13b9ef6edbcd238a3b6caacfef8ba0e5affected
  • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 to < b78db9bddc84136f6a0bb49e8883cf200dfb87a8affected
  • bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 to < 0a8cf165566ba55a39fd0f4de172119dd646d39aaffected

Linux Linux

Default version status: affected

  • 5.12affected
  • 0 to < 5.12unaffected
  • 5.15.210 to ≤ 5.15.*unaffected
  • 6.1.176 to ≤ 6.1.*unaffected
  • 6.6.140 to ≤ 6.6.*unaffected
  • 6.12.86 to ≤ 6.12.*unaffected
  • 6.18.35 to ≤ 6.18.*unaffected
  • 7.0.2 to ≤ 7.0.*unaffected
  • 7.1 to ≤ *unaffected

References