CVE-2026-39421 MEDIUM

CVE-2026-39421: MaxKB: Sandbox escape via ctypes and unhooked SYS_pkey_mprotect

Vendor 1Panel-Dev
Product MaxKB
Weakness CWE-693
Published April 14, 2026
Last update April 14, 2026

CVSS base score

6.3/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

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

What the vulnerability does

01Description

MaxKB is an open-source AI assistant for enterprise. Versions 2.7.1 and below contain a sandbox escape vulnerability in the ToolExecutor component. By leveraging Python's ctypes library to execute raw system calls, an authenticated attacker with workspace privileges can bypass the LD_PRELOAD-based sandbox.so module to achieve arbitrary code execution via direct kernel system calls, enabling full network exfiltration and container compromise. The library intercepts critical standard system functions such as execve, system, connect, and open. It also intercepts mprotect to prevent PROT_EXEC (executable memory) allocations within the sandboxed Python processes, but pkey_mprotect is not blocked. This issue has been fixed in version 2.8.0.

Key dates

02Disclosure timeline

April 14, 2026 CVE published
April 14, 2026 Record updated