RCE in 1panel-Dev Maxkb
CVE-2026-39421
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.
Vulnerability class: RCE (Remote Code Execution)
EPSS: 0.003 (18.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L.
Affected products
- 1panel-dev Maxkb — versions < 2.8.0
- Maxkb
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-39421?
- CVE-2026-39421 is a medium-severity vulnerability in 1panel-Dev Maxkb, classified under Code Injection. CVSS score: 6.3/10. Published 2026-04-14.
- How severe is CVE-2026-39421?
- Medium severity. CVSS v3 base score is 6.3 out of 10.