CVE-2026-77521CWE-250CWE-749CWE-78command-injection

CVE-2026-77521

Critical · published September 22, 2026

CVSS v3.1
10.0
EPSS
1%
Percentile
64.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
10.0 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.01049 · 64.0th percentile
Weaknesses
CWE-250 · Execution with Unnecessary Privileges; CWE-749 · Exposed Dangerous Method or Function; CWE-78 · Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Published
2026-09-22T01:17Z
References (4)
EPSS history
Timeline
  • 23 SEP 03:48Z
    EPSS moved — → 1%
    epss
  • 21 SEP 20:45Z
    MaxKB: Prompt-injectable agent can lead to command execution
    cvelistv5