Medium 5.5Published May 1, 2026

CVE-2026-31704ksmbd: use check_add_overflow() to prevent u16 DACL size overflow

Updated under an hour ago (Oct 27, 2026, 8:40 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use check_add_overflow() to prevent u16 DACL size overflow set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes in u16 variables. When a file has many POSIX ACL entries, the accumulated size can wrap past 65535, causing the pointer arithmetic (char *)pndace + *size to land within already-written ACEs. Subsequent writes then overwrite earlier entries, and pndacl->size gets a truncated value. Use check_add_overflow() at each accumulation point to detect the wrap before it corrupts the buffer, consistent with existing check_mul_overflow() usage elsewhere in smbacl.c.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 before 41e53a773db6342ac9a689ee5ba635c31744c9f0; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 before 8d5729350b236896f51379588d9a690b7fafb8db; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 before e1955a94b6f17f4b058afa955a6f187eb3ed7615; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 before 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 before ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7; from e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 before 299f962c0b02d048fb45d248b4da493d03f3175d	CNA record
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
linux linux_kernel linux:linux_kernel	from 5.15 before 6.6.136; from 6.7 before 6.12.84; from 6.13 before 6.18.25; from 6.19 before 7.0.2	NVD

References

References

https://git.kernel.org/stable/c/41e53a773db6342ac9a689ee5ba635c31744c9f0
https://git.kernel.org/stable/c/8d5729350b236896f51379588d9a690b7fafb8db	patch
https://git.kernel.org/stable/c/e1955a94b6f17f4b058afa955a6f187eb3ed7615	patch
https://git.kernel.org/stable/c/5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43	patch
https://git.kernel.org/stable/c/ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7	patch
https://git.kernel.org/stable/c/299f962c0b02d048fb45d248b4da493d03f3175d	patch
https://cert-portal.siemens.com/productcert/html/ssa-784472.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.