CVE-2026-84809
Received Received - Intake

Tencent AI-Infra-Guard skill-scan compiled Python bytecode bypass

Publication date: 2026-09-02

Last updated on: 2026-09-02

Assigner: VulnCheck

Description
Tencent AI-Infra-Guard's skill-scan component excludes compiled Python bytecode files from analysis by hardcoding __pycache__ directories and .pyc/.pyo/.pyd extensions into skip lists across multiple scanning surfaces. Attackers can distribute skills with benign Python source files alongside malicious compiled bytecode that executes on import while the scanner reports a safe verdict, enabling code execution when operators install the skill.

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Meta Information

Published
2026-09-02
Last Modified
2026-09-02
Generated
2026-09-02
AI Q&A
2026-09-02
EPSS Evaluated
N/A
NVD
CVE-2026-84809
EUVD
EUVD-2026-70224

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
tencent ai-infra-guard From 0 (inc) to 4.5.2 (exc)
tencent ai-infra-guard 4.6.0
tencent ai-infra-guard 4.5.1

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-693 The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

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Executive Summary

This vulnerability involves AI-Infra-Guard's skill-scan tool ignoring compiled Python bytecode files (.pyc, .pyo, .pyd) and __pycache__ directories during security scans. Attackers exploit this by including malicious bytecode alongside clean source code. When the skill is installed, Python executes the bytecode at import time, bypassing the scanner's detection and allowing arbitrary code execution.

Detection Guidance

Check for presence of __pycache__ directories and .pyc/.pyo/.pyd files in scanned directories. Use commands like 'find /path/to/skill -name "__pycache__" -o -name "*.pyc" -o -name "*.pyo" -o -name "*.pyd"' to locate these files. If AI-Infra-Guard is used, ensure it scans these files by verifying the tool's configuration excludes nothing critical.

Inspect AI-Infra-Guard logs for 'compiled-bytecode' warnings or errors. Run 'grep -r "compiled-bytecode" /var/log/ai-infra-guard/' to check for detection attempts. Compare pre-scan results with actual directory contents to identify mismatches.

Impact Analysis

If you use AI-Infra-Guard to scan AI skills or agents, this flaw could allow attackers to hide malicious code in bytecode files. The scanner would falsely report the skill as safe, leading to code execution when the skill is installed or imported. This could compromise systems, exfiltrate data, or establish persistence without detection.

Compliance Impact

This vulnerability could lead to unauthorized code execution, potentially violating data protection requirements under GDPR (e.g., unauthorized processing) and HIPAA (e.g., unauthorized access to protected health information). Organizations using AI-Infra-Guard may fail compliance audits if malicious skills bypass security scans, exposing sensitive data.

Mitigation Strategies

Upgrade AI-Infra-Guard to version 4.5.2 or later where the vulnerability is fixed. If upgrading isn't possible, manually add __pycache__ and .pyc/.pyo/.pyd files to the scanner's skip lists to ensure they are audited.

Review all installed skills for unexpected .pyc files. Remove any .pyc files not matching source code and audit their origins. Disable automatic execution of .pyc files if possible by setting PYTHONDONTWRITEBYTECODE=1 in environment variables.

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