1Panel-dev MaxKB up to 2.7.x Tool Debug API sandbox.so LD_PRELOAD protection mechanism

Summaryinfo

A vulnerability marked as critical has been reported in 1Panel-dev MaxKB up to 2.7.x. The impacted element is an unknown function of the file sandbox.so of the component Tool Debug API. The manipulation of the argument LD_PRELOAD leads to protection mechanism. This vulnerability is documented as CVE-2026-39420. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in 1Panel-dev MaxKB up to 2.7.x. This issue affects an unknown code of the file sandbox.so of the component Tool Debug API. The manipulation of the argument LD_PRELOAD with an unknown input leads to a protection mechanism vulnerability. Using CWE to declare the problem leads to CWE-693. The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

MaxKB is an open-source AI assistant for enterprise. In versions 2.7.1 and below, an incomplete sandbox protection mechanism allows an authenticated user with tool execution privileges to escape the LD_PRELOAD-based sandbox. By env command the attacker can clear the environment variables and drop the sandbox.so hook, leading to unrestricted Remote Code Execution (RCE) and network access. MaxKB restricts untrusted Python code execution via the Tool Debug API by injecting sandbox.so through the LD_PRELOAD environment variable. This intercepts sensitive C library functions (like execve, socket, open) to restrict network and file access. However, a patch allowed the /usr/bin/env utility to be executed by the sandboxed user. When an attacker is permitted to create subprocesses, they can execute the env -i python command. The -i flag instructs env to completely clear all environment variables before running the target program. This effectively drops the LD_PRELOAD environment variable. The newly spawned Python process will therefore execute natively without any sandbox hooks, bypassing all network and file system restrictions. This issue has been fixed in version 2.8.0.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-39420 since 04/07/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details are known, but no exploit is available.

Upgrading to version 2.8.0 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 2d17b08e6b060329803754a05e806d0ddecf3fa8 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• 1Panel-dev

Name

• MaxKB

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7

License

• open-source

Website

• Product: https://github.com/1Panel-dev/MaxKB/

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