Summary
Claude Code: Plugin Hash Pin Bypass Allows Bypass of Hash Pinning
The plugin install flow in Claude Code and Claude Desktop checked out a marketplace's pinned commit SHA using git checkout without verifying that the resulting HEAD matched the pinned SHA. An attacker controlling a plugin's upstream repository could create a branch named identically to the pinned 40-character SHA, causing the checkout to silently resolve to the attacker's branch tip instead of the reviewed commit, resulting in attacker-controlled code being installed bypassing the pinned hash. Exploitation required a user to install a malicious plugin, pin to a safe hash, and for the plugin source to be hosted on a git host that permitted SHA-shaped branch names.
Users on standard Claude Code auto-update have received this fix already. Users performing manual updates are advised to update to the latest version.
Thank you to Or Nevo Michrowski of Air Security for reporting this issue.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-86063? CVE-2026-86063 is a high-severity security vulnerability in @anthropic-ai/claude-code (npm), affecting versions < 2.1.179. It is fixed in 2.1.179.
- Which versions of @anthropic-ai/claude-code are affected by CVE-2026-86063? @anthropic-ai/claude-code (npm) versions < 2.1.179 is affected.
- Is there a fix for CVE-2026-86063? Yes. CVE-2026-86063 is fixed in 2.1.179. Upgrade to this version or later.
- Is CVE-2026-86063 exploitable, and should I be worried? Whether CVE-2026-86063 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-86063 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-86063? Upgrade
@anthropic-ai/claude-codeto 2.1.179 or later.