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().
References
Configurations
Configuration 1 (hide)
|
History
30 Oct 2026, 14:29
| Type | Values Removed | Values Added |
|---|---|---|
| CPE | cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* |
|
| First Time |
Linux linux Kernel
Linux |
|
| CWE | CWE-125 | |
| References | () https://git.kernel.org/stable/c/0e60dafe97eca61721f3db456f97d97a80c6c8ae - Patch | |
| References | () https://git.kernel.org/stable/c/0fe08c5776a798f46df1fd74b331be26bdd644d6 - Patch | |
| References | () https://git.kernel.org/stable/c/4f7c131d2bdd7cd64b96f60d10be5ea72253f520 - Patch | |
| References | () https://git.kernel.org/stable/c/5500ba1d410aed1eded3eb04a76b10cfb4409334 - Patch | |
| References | () https://git.kernel.org/stable/c/94215d55b09445993929f4fc966061d61de74929 - Patch | |
| References | () https://git.kernel.org/stable/c/d333af32e4451285e427f2d9c29de3a39f6f6d48 - Patch | |
| References | () https://git.kernel.org/stable/c/f6324b4240cf0b26a84c33f68a1222d727ff4af2 - Patch |
Information
Published : 2026-07-19 16:17
Updated : 2026-10-30 14:29
NVD link : CVE-2026-63909
Mitre link : CVE-2026-63909
CVE.ORG link : CVE-2026-63909
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-125
Out-of-bounds Read