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Permalink CVE-2026-63909
8.1 HIGH
  • CVSS version (CVSS): 3.1
  • Attack Vector (AV): Network (N)
  • Attack Complexity (AC): Low (L)
  • Privileges Required (PR): Low (L)
  • User Interaction (UI): None (N)
  • Scope (S): Unchanged (U)
  • Confidentiality (C): High (H)
  • Integrity (I): None (N)
  • Availability (A): High (H)
  • Modified Attack Vector (MAV): Network (N)
  • Modified Attack Complexity (MAC): Low (L)
  • Modified Privileges Required (MPR): Low (L)
  • Modified User Interaction (MUI): None (N)
  • Modified Confidentiality (MC): High (H)
  • Modified Scope (MS): Unchanged (U)
  • Modified Integrity (MI): None (N)
  • Modified Availability (MA): High (H)
created 6 days, 2 hours ago Activity log
  • Created & dismissed (max. allowed matches exceeded) suggestion
ksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops

In the Linux kernel, the following vulnerability has been resolved: ksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops Commit d07b26f39246 ("ksmbd: require minimum ACE size in smb_check_perm_dacl()") introduced a transposed bounds check: if (offsetof(struct smb_ace, sid) + aces_size < CIFS_SID_BASE_SIZE) Since offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates to `aces_size < 0`. Because `aces_size` is always non-negative, this check becomes dead code and never breaks the loop. Worse, that commit removed the old 4-byte guard, meaning the loop now reads `ace->size` (offset 2) even when `aces_size` is 0-3 bytes. This re-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation during subsequent SMB2_CREATE operations. Fix this by properly transposing the comparison to require at least 16 bytes (8-byte offset + 8-byte SID base), matching the correct form used in smb_inherit_dacl().

Affected products

Linux
  • <6.18.35
  • <f6324b4240cf0b26a84c33f68a1222d727ff4af2
  • <4f7c131d2bdd7cd64b96f60d10be5ea72253f520
  • <94215d55b09445993929f4fc966061d61de74929
  • <7.0.12
  • <d333af32e4451285e427f2d9c29de3a39f6f6d48
  • <5500ba1d410aed1eded3eb04a76b10cfb4409334
  • <0fe08c5776a798f46df1fd74b331be26bdd644d6
  • <6.6.143
  • <6.12.93
  • <0e60dafe97eca61721f3db456f97d97a80c6c8ae