Out-of-bounds read in Linux kernel - CVE-2026-31712

Detailed vulnerability description

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to an out-of-bounds read in smb_check_perm_dacl() when processing a crafted DACL during SMB permission checks. A remote user can set a crafted ACL on a file they own and trigger a subsequent CREATE request to cause a denial of service.

The issue is reachable by an authenticated SMB client with permission to set an ACL on a file, and it is not pre-authentication. The out-of-bounds read is not reflected to the attacker, but KASAN reports and kernel state corruption are possible.

How to mitigate CVE-2026-31712

Sources

• https://git.kernel.org/stable/c/151b1799861fde38087c08f613abc2843ef597b0
• https://git.kernel.org/stable/c/90089584b2e25c4510b7b987387b4405f0673ece
• https://git.kernel.org/stable/c/95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c
• https://git.kernel.org/stable/c/d07b26f39246a82399661936dd0c853983cfade7