TL;DR
Researchers cited by Thorsten Meyer AI, Mitiga Labs, Check Point Research and Computerwoche have documented Claude Code security risks tied to local configuration, MCP connectors and repository hooks. Anthropic has patched reported Check Point vulnerabilities, while a Mitiga Labs token-theft chain remains described as unpatched and treated by Anthropic as out of scope.
Security researchers have disclosed Claude Code attack paths that could expose developer tokens or run code through local configuration, MCP integrations and repository hooks, affecting teams that connect coding agents to GitHub, Jira, Confluence and internal systems.
The source material identifies three reported issues. Mitiga Labs described a token-theft path in which a malicious npm package uses a post-install hook to rewrite ~/.claude.json, redirect Claude Code’s authenticated MCP traffic and intercept long-lived OAuth tokens tied to connected services. According to the material, that chain has not been patched.
Check Point Research separately reported two vulnerabilities listed in the source material as CVE-2025-59536, a remote code execution issue through repository hooks, and CVE-2026-21852, an API-key exfiltration flaw. The article says Anthropic patched those issues after responsible disclosure.
SecurityWeek and all-about-security are also cited for reporting that a packaging error exposed unencrypted source code, which the source material says has since been used in fake GitHub repositories distributing trojans through social engineering. The material does not establish how many developers or organizations were affected.
Your Coding Agent Is an Attack Surface
● SecurityThree disclosed flaws turned Claude Code’s local config and MCP integrations into silent paths for token theft and code execution. Some fixes are yours to make — and the lesson applies to every agentic dev tool, not one.
The config files most teams treat as passive metadata are, in practice, active execution paths.
~/.claude.json, reroutes MCP traffic, and intercepts long-lived OAuth tokens for GitHub, Jira, Confluence.How the unpatched Mitiga path works — at the level its researchers published. (Defensive overview, no exploit detail.)
~/.claude.json.For teams running Claude Code — or any coding agent — in production.
~/.claude.json/permissions; disconnect what you don’t use.Anthropic patched the Check Point CVEs fast — responsible disclosure worked. The npm post-install hook is an industry-wide supply-chain risk class, not Anthropic’s invention.
Anthropic calls the Mitiga chain “out of scope.” But consenting to install a package isn’t consenting to having your SaaS credentials intercepted — and plaintext tokens in the router file turn a generic risk into a specific one.
Independent commentary, produced with AI assistance under human editorial oversight; the views are the author’s own and may change. This is security analysis and opinion, not professional security, legal, or financial advice; verify specifics against vendor advisories and the primary research before acting. It describes publicly disclosed vulnerabilities at the level reported by their researchers and is for defensive purposes only — no exploit code or attack instructions. Sources: Computerwoche (Anjali Gopinadhan Nair), Mitiga Labs, Check Point Research, SecurityWeek, all-about-security, and Anthropic’s documentation, read as of June 2026. References to companies, researchers, and CVEs are factual and analytical and imply no affiliation or endorsement.
Agent Tokens Can Expose Connected Services
The disclosed risks concern coding agents that operate near source code, build systems, cloud credentials, issue trackers and internal APIs. If a connected agent’s OAuth token is stolen, the attacker may gain access that reflects the agent’s permissions across several services.
The source material describes the Mitiga Labs chain as distinct from ordinary browser phishing because the traffic can appear to come from authenticated Claude Code activity by a real user. That may affect detection methods focused mainly on unusual login origins or clearly abnormal user behavior.
For organizations that run agentic development tools in production workflows, the material points to controls covering package install scripts, agent config drift, MCP endpoint changes and token scope reviews.
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Config Files Can Affect Agent Behavior
Claude Code and similar agentic tools are designed to work on a developer’s machine and connect to outside systems through integrations such as MCP. Those capabilities can place them close to sensitive credentials and actions.
The source material says German-market commentary in Computerwoche by cybersecurity engineer Anjali Gopinadhan Nair tied the recent disclosures together around one shared pattern: local files, repo hooks and connector settings can influence what the agent runs, where traffic goes and which credentials are exposed.
Anthropic is credited in the material with patching the Check Point Research issues. The material says Anthropic considers the Mitiga Labs chain out of scope, while Mitiga Labs describes the token-routing behavior as a user-side risk.
Exploitation Scope Still Unknown
It is not yet clear from the source material how broadly any of the disclosed paths have been exploited against real development teams. The material describes reported lures and a token-theft chain, but it does not provide victim counts, affected organizations or forensic evidence from confirmed intrusions.
It is also unclear whether Anthropic will change its position on the Mitiga Labs path. The article says the company treats the npm post-install route as out of scope, while the source material says the plaintext token-routing behavior creates a tool-specific risk.
Teams Review Agent Controls
The next step identified in the source material is defensive review. The source material recommends updating Claude Code, monitoring ~/.claude.json for new MCP endpoints or proxy changes, reviewing npm post-install hooks, removing malicious hooks before rotating tokens, narrowing MCP scopes and disconnecting unused services.
Security teams may also review vendor guidance, detections and follow-up research across other agentic developer tools. A related issue is whether coding-agent configuration should be governed like production code, with review, provenance checks and least-privilege access.
Key Questions
What was disclosed about Claude Code?
The source material says researchers documented attack paths involving Claude Code’s local configuration, MCP integrations, repository hooks and package install behavior. Two Check Point Research CVEs are described as patched, while the Mitiga Labs token-theft path is described as still unresolved.
What is the Mitiga Labs token-theft chain?
According to the source material, Mitiga Labs described a malicious npm package that can rewrite ~/.claude.json, redirect authenticated MCP traffic and capture long-lived OAuth tokens for connected services.
Did Anthropic fix the reported vulnerabilities?
The material says Anthropic patched the Check Point Research issues after responsible disclosure. It also says Anthropic considers the Mitiga Labs npm post-install chain out of scope, leaving that path for users and teams to mitigate.
Why does this matter beyond Claude Code?
The same pattern can apply to other coding agents that run locally, connect to SaaS tools and act with developer permissions. The risk is tied to the agentic development model, not only one product.
What should teams do now?
Teams should update Claude Code, audit MCP permissions, watch config changes, review package install scripts, isolate agent sessions where possible and rotate tokens after removing any malicious persistence path.
Source: Thorsten Meyer AI
