If you’re running Claude Code CLI in any CI/CD pipeline, stop what you’re doing and check your version. Right now.

Three newly registered CVEs — CVE-2026-35020, CVE-2026-35021, and CVE-2026-35022 — are command injection flaws in Claude Code CLI that researchers at phoenix.security validated as exploitable on v2.1.91 as recently as April 3, 2026. They chain together to enable credential exfiltration over plain HTTP, and every one of them carries a CVSS score of 9.8 (Critical). On top of that, Anthropic shipped a separate patch on April 6 for a distinct high-severity deny-rule bypass — both security issues trace back to the same Claude Code source leak.

This is not a theoretical disclosure. There is timestamped callback evidence.

The Root Cause: One Leak, Three Chains

All three CVEs originate from the same underlying problem identified after the Claude Code source leak: insufficient sanitization of user-controlled input before it reaches shell execution sinks. Each CVE exploits a slightly different pathway, but when chained, the effect is devastating:

  1. CVE-2026-35020 — Zero-interaction command execution via environment variable injection. An attacker who can control an environment variable in a CI/CD context can trigger arbitrary shell commands with no user prompt required.

  2. CVE-2026-35021 — POSIX shell double-quote bypass via file path. Crafted file paths escape their intended context and execute as shell commands. This is particularly dangerous in agentic workflows where Claude Code operates autonomously on file trees it doesn’t fully control.

  3. CVE-2026-35022 — Three distinct exploitation modes: local shell command chaining, credential-format evasion to bypass content filters, and HTTP callback exfiltration. That third mode is where things get truly ugly: credentials, file contents, and even conversation history can be silently sent to an attacker-controlled endpoint.

The compound risk in CI/CD environments is significant. Automated pipelines rarely have the human-in-the-loop oversight that catches anomalous outbound HTTP calls, especially during long-running agentic tasks.

The April 6 Bypass Patch

Separate from the CVE trio, Anthropic shipped a patch on April 6 addressing a high-severity deny-rule bypass in Claude Code. This is the second major security fix in less than a week, both rooted in the same source code exposure event. The bypass allowed attackers to circumvent explicitly configured deny rules — the safety guardrails that operators use to restrict what Claude Code is permitted to do in their environments.

For teams that deployed Claude Code with custom deny rules believing they were protected, that assumption may have been wrong until this patch landed.

What You Should Do Right Now

Check your version. If you’re on v2.1.91 or earlier, you are vulnerable. Pull the latest release from Anthropic’s official distribution channels immediately.

Audit your CI/CD environment variables. CVE-2026-35020 specifically targets env var injection. Review which pipeline variables are accessible to Claude Code execution contexts, and apply principle of least privilege.

Inspect outbound HTTP logs. If you have Claude Code running in production or CI/CD pipelines, look back through your HTTP egress logs for any unexpected callback requests, particularly to non-Anthropic domains.

Validate your deny rules. Even after patching the bypass, it’s worth auditing your configured deny rules to confirm they reflect your intended security posture.

Isolate agentic workloads. For teams running Claude Code autonomously on untrusted file trees, consider network isolation — restricting outbound HTTP from the execution environment to known-good endpoints only.

The Bigger Picture

These disclosures arrive at an uncomfortable moment for the agentic AI industry. Developers have been racing to integrate tools like Claude Code into production CI/CD pipelines, automated code review workflows, and autonomous engineering agents. The attack surface is expanding faster than security practices are maturing.

The source leak that enabled this discovery was itself a significant event. It demonstrates that even frontier AI companies are not immune to the same infrastructure security failures that affect any software organization. When source code leaks, it gives vulnerability researchers — and adversaries — a much more targeted view of where to look.

Three CVSS 9.8 vulnerabilities chaining to credential exfiltration is not a minor bug report. It’s a wake-up call for every team treating Claude Code as a trusted participant in their infrastructure.

Patch. Audit. Isolate. In that order.

Sources

  1. Three CVEs in Claude Code CLI and the Chain That Connects Them — phoenix.security
  2. CVE-2026-35021 entry — tenable.com
  3. CVE-2026-35022 coverage — thehackerwire.com
  4. Claude Code deny-rule bypass patch — cybersecuritynews.com
  5. CVE registry cross-reference — cvefeed.io

Researched by Searcher → Analyzed by Analyst → Written by Writer Agent (Sonnet 4.6). Full pipeline log: subagentic-20260407-0800

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