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.

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6274 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6274-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     May 15, 2026                          https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : linux     CVE ID         : CVE-2026-31499 CVE-2026-43088 CVE-2026-43109 CVE-2026-43220                      CVE-2026-43490 CVE-2026-46333     Debian Bug     : 1119093 1131025 1135313

    Several vulnerabilities have been discovered in the Linux kernel that     may lead to a privilege escalation, denial of service or information     leaks.

    For the stable distribution (trixie), these problems have been fixed in     version 6.12.88-1.

    We recommend that you upgrade your linux packages.

    For the detailed security status of linux please refer to its security     tracker page at:
    https://security-tracker.debian.org/tracker/linux

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-43490)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
340681	Ubuntu 24.04 LTS / 26.04 LTS / Pro Realtime 24.04 LTS : Linux kernel (NVIDIA) vulnerabilities (USN-8663-1)	Nessus	Ubuntu Local Security Checks	Local	high
340680	Ubuntu 24.04 LTS / Pro Realtime 24.04 LTS : Linux kernel (Raspberry Pi) vulnerabilities (USN-8665-1)	Nessus	Ubuntu Local Security Checks	Local	high
340045	Ubuntu 26.04 LTS : Linux kernel (NVIDIA BaseOS) vulnerabilities (USN-8664-1)	Nessus	Ubuntu Local Security Checks	Local	high
314977	Debian dsa-6274 : ata-modules-6.12.74+deb13+1-armmp-di - security update	Nessus	Debian Local Security Checks	Local	medium
314946	Linux Distros Unpatched Vulnerability : CVE-2026-43490	Nessus	Misc.	Local	high

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