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CVE-2026-43490

Out-of-bounds Write: is CVE-2026-43490real, exploitable, or a false positive? Here's the community verdict.

signals

public sources

Exploited in wild
Not listed
CISA KEV
Base severity
8.8 High
CVSS
Exploitation prob.
0.4%
FIRST EPSS
Weakness
CWE-787 · Out-of-bounds Write
CWE

High CVSS base score, but low real-world exploitation probability (EPSS). Likely less urgent than the score implies.

baseline read

auto · not a community verdict

Real, but low real-world risk

A genuine vulnerability on paper, but EPSS shows little real-world exploitation — the base score may overstate urgency. This is not the same as a false positive.

Based on CVSS · FIRST EPSS

Confirm or dispute →
Affected:Linux

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate inherited ACE SID length smb_inherit_dacl() walks the parent directory DACL loaded from the security descriptor xattr. It verifies that each ACE contains the fixed SID header before using it, but does not verify that the variable-length SID described by sid.num_subauth is fully contained in the ACE. A malformed inheritable ACE can advertise more subauthorities than are present in the ACE. compare_sids() may then read past the ACE. smb_set_ace() also clamps the copied destination SID, but used the unchecked source SID count to compute the inherited ACE size. That could advance the temporary inherited ACE buffer pointer and nt_size accounting past the allocated buffer. Fix this by validating the parent ACE SID count and SID length before using the SID during inheritance. Compute the inherited ACE size from the copied SID so the size matches the bounded destination SID. Reject the inherited DACL if size accumulation would overflow smb_acl.size or the security descriptor allocation size.

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    Same weakness: CWE-787 · Out-of-bounds Write.