GitHub Actions Supply Chain Attack Redirects Tags to Steal CI/CD Credentials  Ravie Lakshmanan  May 19, 2026 Software Security / Malware In yet another software supply chain attack, threat actors have compromised the popular GitHub Actions workflow, actions-cool/issues-helper, to run malicious code that harvests sensitive credentials and exfiltrates them to an attacker-controlled server. "Every existing tag in the repository has been moved to point to an imposter commit that does not appear in the action's normal commit history," StepSecurity researcher Varun Sharma said . "That commit contains malicious code that exfiltrates credentials from CI/CD pipelines that run the action." An imposter commit refers to a deceptive software supply chain attack strategy in which malicious code is injected into a project by referencing a commit or tag that exists only in an adversary-controlled fork, rather than the original trusted repository. As a result, attackers can bypass standard Pull Request (PR) reviews and achieve arbitrary code execution. The imposter commit, per the cybersecurity company, contains code that, upon being executed within a GitHub Actions runner, performs a series of actions - Downloads the Bun JavaScript runtime to the runner. Reads memory from the Runner.Worker process to extract credentials. Makes an outbound HTTPS call to an attacker-controlled domain ("t.m-kosche[.]com") to transmit the stolen data. StepSecurity said 15 tags associated with a second GitHub action, "actions-cool/maintain-one-comment" have also been compromised with the same functionality. GitHub has since disabled access to the repository due to a "violation of GitHub's terms of service." It's currently not known what led the Microsoft-owned subsidiary to this decision. Interestingly, the exfiltration domain "t.m-kosche[.]com" has been observed in the latest wave of the Mini Sha-Hulud campaign targeting npm packages from the @antv ecosystem, indicating the two clusters of activity could be related. "Because every tag now resolves to malicious commits, any workflow that references the action by version pulls the malicious code on its next run," StepSecurity said. "Only workflows pinned to a known-good full commit SHA are unaffected." Found this article interesting? Follow us on Google News , Twitter and LinkedIn to read more exclusive content we post. SHARE      Tweet  Share  Share  Share   Share on Facebook  Share on Twitter  Share on Linkedin  Share on Reddit  Share on Hacker News  Share on Email  Share on WhatsApp Share on Facebook Messenger  Share on Telegram SHARE  CI/CD , Credential Theft , cybersecurity , GitHub Actions , Malware , Mini Sha-Hulud , NPM , Software Security , StepSecurity , Supply Chain Attack ⚡ Top Stories This Week Ollama Out-of-Bounds Read Vulnerability Allows Remote Process Memory Leak Four OpenClaw Flaws Enable Data Theft, Privilege Escalation, and Persistence On-Prem Microsoft Exchange Server CVE-2026-42897 Exploited via Crafted Email Cisco Catalyst SD-WAN Controller Auth Bypass Actively Exploited to Gain Admin Access ThreatsDay Bulletin: PAN-OS RCE, Mythos cURL Bug, AI Tokenizer Attacks, and 10+ Stories Windows Zero-Days Expose BitLocker Bypasses And CTFMON Privilege Escalation New Fragnesia Linux Kernel LPE Grants Root Access via Page Cache Corruption 18-Year-Old NGINX Rewrite Module Flaw Enables Unauthenticated RCE Microsoft's MDASH AI System Finds 16 Windows Flaws Fixed in Patch Tuesday [Webinar] How Modern Attack Paths Cross Code, Pipelines, and Cloud Microsoft Patches 138 Vulnerabilities, Including DNS and Netlogon RCE Flaws New Exim BDAT Vulnerability Exposes GnuTLS Builds to Potential Code Execution Mini Shai-Hulud Worm Compromises TanStack, Mistral AI, Guardrails AI and More Packages cPanel CVE-2026-41940 Under Active Exploitation to Deploy Filemanager Backdoor ⚡ Weekly Recap: Linux Rootkit, macOS Crypto Stealer, WebSocket Skimmers and More Hackers Used AI to Develop First Known Zero-Day 2FA Bypass for Mass Exploitation ⭐ Featured Resources [Webinar] Learn How to Handle Critical SOC Alerts With AI Support Identify Internal Attack Surfaces More Efficiently With a Free Assessment [eBook] Get the 3-Number SOC Diagnostic to Reduce Queue Risk [Guide] Stop Email Fraud Before It Turns Into Ransomware Damage