Report: Complete Guide to CVE-2026-39421 - MaxKB: Sandbox escape via ctypes and unhooked SYS_pkey_mprotect

Report: Complete Guide to CVE-2026-39421 - MaxKB: Sandbox escape via ctypes and unhooked SYS_pkey_mprotect

CVE ID :CVE-2026-39421 Published : April 14, 2026, 1:16 a.m. | 39 minutes ago Description :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. Severity: 6.3 | MEDIUM Visit the link for more details, such as CVSS details, affected products, timeline, and more...

CVE Details

Severity
CRITICAL
Published
April 14, 2026
Affected Product: Python
Attack Vector: network
Impact: code execution