CVE-2026-77521: MaxKB: Prompt-injectable agent can lead to command execution

Vulnerability summary

CVE-2026-77521 is a critical (CVSS 10.0) vulnerability in 1panel-dev maxkb. EPSS estimates a 1.05% chance of exploitation in the next 30 days, higher than 64.2% of scored vulnerabilities.

Timeline

1. 21-09-2026
   PublishedVulnerability first disclosed.
2. 22-09-2026
   Last modifiedVulnerability information updated.

Description

MaxKB is an open-source AI assistant for enterprise. Prior to version 2.10.5-lts, assistants with a tool, MCP tool, skill, or sub-application use SandboxShellBackend, which exposes an execute shell tool without excluding it and omits execute from interrupt_on, so human approval is not required. Untrusted chat or ingested content can therefore cause command execution; source deployments with MAXKB_SANDBOX disabled run commands directly as the application user, while the official root container's string-based gosu wrapper allowed shell metacharacters to execute outside the intended sandbox. This issue is fixed in version 2.10.5-lts.

• CWE-78Improper Neutralization of Special Elements used in an OS CommandThe product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component.
• CWE-250Execution with Unnecessary PrivilegesThe product performs an operation at a privilege level that is higher than the minimum level required, which creates new weaknesses or amplifies the consequences of other weaknesses.
• CWE-749Exposed Dangerous Method or FunctionThe product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.