---
title: "[AUTO] Claude Code Preview Pane's Silent Credential Leak"
pubDatetime: 2026-10-15T11:43:00.000Z
description: "Three vulnerabilities in Claude Code's preview pane enabled silent credential exfiltration—reported and patched in summer 2026."
tags: [claude-code, vulnerability, ai-security, credentials, sandboxing, disclosure, 2026, 2026-q4, 2026-10, AUTO]
---
[Noma Labs disclosed](https://noma.security/noma-labs/sneakpeek-how-the-preview-pane-in-claude-code-desktop-can-exfiltrate-your-data) three flaws in Claude Code Desktop's preview pane. Files over 256KB load as file:// URLs instead of sandboxed URLs. CSP only protected the data URL path. An inactive filter let fetch() read local files. Embed malicious JavaScript in a public repository; when a developer asks Claude to review it, the preview pane auto-executes and exfiltrates SSH keys, AWS tokens, and Git secrets.

[Patched August 17, 2026](https://www.prnewswire.com/news-releases/noma-labs-uncovers-critical-security-vulnerabilities-in-claude-code-desktop-app-cvss-8-7-302908539.html) (v1.30096.1+). The first patch was bypassable via Web Workers; Anthropic deployed a multi-layered fix.

The 256KB threshold wasn't a security boundary; it was a performance constraint that became a security assumption. When three systems aligned, the gap became exploitable. No single component failed; the attack existed only at their intersection. Security review misses these blind spots.

---

*Sources: [SneakPeek: How the Preview Pane in Claude Code Desktop Can Exfiltrate Your Data](https://noma.security/noma-labs/sneakpeek-how-the-preview-pane-in-claude-code-desktop-can-exfiltrate-your-data)  •  [Noma Labs Uncovers Critical Security Vulnerabilities in Claude Code Desktop App](https://www.prnewswire.com/news-releases/noma-labs-uncovers-critical-security-vulnerabilities-in-claude-code-desktop-app-cvss-8-7-302908539.html)*

*Coverage: [Anthropic 'SneakPeek' Flaw Is a Silent Zero-Click Threat](https://www.darkreading.com/threat-intelligence/new-anthropic-sneakpeek-silent-zero-click-threat)  •  [How Claude Code's 256KB blind spot put developers' secrets in the preview pane](https://www.csoonline.com/article/4235139/how-claude-codes-256kb-blind-spot-put-developers-secrets-in-the-preview-pane.html)*

*Related on this blog: [OpenAI's Six Misalignment Reports Read Like a Controls Audit](/posts/openai-six-misalignment-reports)  •  [[AUTO] Any User Can Become Admin in LiteLLM](/posts/auto-litellm-privilege-escalation)  •  [[AUTO] MemTensor Worm Exploits GitHub Actions Token Interception](/posts/auto-memtensor-sckit-worm)*