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2026-04-15 · 2026-Q2

Claude Code, Gemini CLI, Copilot Agent Hijacked via GitHub Comments

PrimaryL2InstructionSecondaryL1CredentialL6Identity / Run
Fixable:
No, architectural
Vendor response:
Unknown
In the wild:
No
Actor:
Attacker

Target

Anthropic Claude Code Security Review, Google Gemini CLI Action, GitHub Copilot Agent (all GitHub Actions integrations)

Impact

Prompt injection via PR titles, issue descriptions, and comments lets attackers execute arbitrary commands in the Actions runner, steal Anthropic and Gemini API keys, GitHub tokens, and any repository or organization secret available to the workflow

Root Cause

Each agent ingests untrusted GitHub comment content as authoritative instructions with no separation between policy and data; all three vendors paid bug bounties ($100 Anthropic, $500 GitHub, undisclosed Google) but none assigned CVEs or published advisories, leaving downstream users unaware

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