DEBIAN-CVE-2026-31709

Advisory lineage Upstream: 1 Downstream: 0
Upstream
CVE-2026-31709
Published: 01 May 2026, 14:16
Last modified:09 May 2026, 23:00

Vulnerability Summary

Overall Risk (default)
medium
35/100
CVSS Score
8.8 HIGH
3.1 (osv_debian)
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

01 May 2026, 14:16
Published
Vulnerability first disclosed
09 May 2026, 23:00
Last Modified
Vulnerability information updated

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.

CVSS Metrics

  • v3.1•HIGH•Score: 8.8CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Systems

  • debian•linux

    all | all | all | < 6.12.86-1 | < 7.0.3-1

References (1)