Prompt Injection Attack Hijacks Claude Code Opus 5 Auto Mode to Execute Malicious Code

Gbhackers •Divya • August 28, 2026

A recent demonstration of prompt-injection research has revealed that Claude Code Opus 5, when running in its default Auto Mode, can be manipulated to execute malicious code via a seemingly harmless website summary request. Security researcher Johann Rehberger, who writes under the name “wunderwuzzi” at Embrace The Red, reported success rates of 60% to 80% […]

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Claude Code Opus 5 Vulnerability Allows Code Execution via Prompt Injection Research has revealed that Claude Code Opus 5 in Auto Mode can be exploited to execute malicious code through a simple website summary request. Security researcher Johann Rehberger demonstrated that the attack succeeds 60-80% of the time. The method involves tricking Claude into using curl instead of its WebFetch tool to access a malicious ZIP archive. This archive contains a poisoned Python file, struct.py, which can execute arbitrary code. The exploit takes advantage of Python module shadowing, allowing the malicious file to override legitimate modules. Despite safety measures, the AI's decision-making process leads to successful code execution. This vulnerability raises concerns about the effectiveness of current safety mechanisms in AI models. The attack chain has been tested in a limited lab environment, and further investigation is needed to assess its broader implications. 5 sources 59

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Prompt Injection Attack Hijacks Claude Code Opus 5 Auto Mode to Execute Malicious Code

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