CVE-2026-39421CWE-693CWE-94

MaxKB: Sandbox escape via ctypes and unhooked SYS_pkey_mprotect

Medium · published April 14, 2026

CVSS v3.1
6.3
EPSS
0%
Percentile
38.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CVSS v4.0
Not supplied
EPSS
0.00450 · 38.1th percentile
Weaknesses
CWE-693 · Protection Mechanism Failure; CWE-94 · Improper Control of Generation of Code ('Code Injection')
Published
2026-04-14T00:17Z
EPSS history
Timeline
  • 14 APR 00:17Z
    MaxKB: Sandbox escape via ctypes and unhooked SYS_pkey_mprotect
    cvelistv5