labring FastGPT up to 4.14.7 File Descriptor sys.stdout.write incomplete blacklist

Summaryinfo

A vulnerability described as critical has been identified in labring FastGPT up to 4.14.7. This vulnerability affects the function sys.stdout.write of the component File Descriptor Handler. The manipulation results in incomplete blacklist. This vulnerability was named CVE-2026-32128. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in labring FastGPT up to 4.14.7. It has been classified as critical. Affected is the function sys.stdout.write of the component File Descriptor Handler. The manipulation with an unknown input leads to a incomplete blacklist vulnerability. CWE is classifying the issue as CWE-184. The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-32128 since 03/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 03/17/2026). The MITRE ATT&CK project declares the attack technique as T1562.006.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• labring

Name

• FastGPT

Version

• 4.14.0
• 4.14.1
• 4.14.2
• 4.14.3
• 4.14.4
• 4.14.5
• 4.14.6
• 4.14.7

Website

• Product: https://github.com/labring/FastGPT/

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