CVE-2026-21852: Claude Code Data Leak via Malicious Config

# CVE-2026-21852: Claude Code Data Leak via Malicious Config

https://gcdradar.vercel.app/incidents/cve-2026-21852-claude-code-data-leak-via-malicious-config · AIR-2026-0436 · closed 2026-01-21

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-01-21
- AI role: Attack on AI
- Products: Claude Code
- CVE ids: CVE-2026-21852
- CVSS: 5.3

## Summary

A vulnerability in Claude Code allowed malicious repositories to exfiltrate data and API keys before trust confirmation. A patch has been issued via auto-updates.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2026-01-21: CVE-2026-21852: Claude Code is an agentic coding tool. (https://nvd.nist.gov/vuln/detail/CVE-2026-21852)
- 2026-01-21: CVE-2026-21852: Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation (https://github.com/advisories/GHSA-jh7p-qr78-84p7)

## Sources

- 2026-01-21 GitHub Advisory Database: CVE-2026-21852: Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation https://github.com/advisories/GHSA-jh7p-qr78-84p7
- 2026-01-21 NVD: CVE-2026-21852: Claude Code is an agentic coding tool. https://nvd.nist.gov/vuln/detail/CVE-2026-21852

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.