CVE-2026-31704: Linux kernel · ksmbd: use check_add_overflow() to prevent u16 DACL size overflow
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 11 Nov 2026, 23:24 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- EPSS
- 0.1% chance of exploitation in 30 days – higher than 1% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.
Description
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.
References
- git.kernel.org/stable/c/41e53a773db6342ac9a689ee5ba635c31744c9f0 (opens in a new tab)
- git.kernel.org/stable/c/8d5729350b236896f51379588d9a690b7fafb8db (opens in a new tab)
- git.kernel.org/stable/c/e1955a94b6f17f4b058afa955a6f187eb3ed7615 (opens in a new tab)
- git.kernel.org/stable/c/5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 (opens in a new tab)
- git.kernel.org/stable/c/ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 (opens in a new tab)
- git.kernel.org/stable/c/299f962c0b02d048fb45d248b4da493d03f3175d (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)