CVE-2026-39419CWE-290CWE-693CWE-74

MaxKB: Sandbox Result Validation Bypass via Tool Output Spoofing

Low · published April 14, 2026

CVSS v3.1
3.1
EPSS
0%
Percentile
26.9
In the wild
Unconfirmed
What it is

MaxKB is an open-source AI assistant for enterprise. In versions 2.7.1 and below, an authenticated user can bypass sandbox result validation and spoof tool execution results by exploiting Python frame introspection to read the wrapper's UUID from its bytecode constants, then writing a forged result directly to file descriptor 1 (bypassing stdout redirection). By calling sys.exit(0), the attacker terminates the wrapper before it prints the legitimate output, causing the MaxKB service to parse and trust the spoofed response as the genuine tool result. This issue has been fixed in version 2.8.0.

The record
Technical detail
CVSS v3.1
3.1 · LOW
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00346 · 26.9th percentile
Weaknesses
CWE-290 · Authentication Bypass by Spoofing; CWE-693 · Protection Mechanism Failure; CWE-74 · Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Published
2026-04-14T01:03Z
EPSS history
Timeline
  • 14 APR 01:03Z
    MaxKB: Sandbox Result Validation Bypass via Tool Output Spoofing
    cvelistv5