CVE-2026-21852
Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation
- State
- Published
- Severity
- 5.3 Medium
- Published
- Jan 21, 2026
- Updated
- Jan 21, 2026
- Reserved
- Jan 5, 2026
Description
Claude Code is an agentic coding tool. Prior to version 2.0.65, vulnerability in Claude Code's project-load flow allowed malicious repositories to exfiltrate data including Anthropic API keys before users confirmed trust. An attacker-controlled repository could include a settings file that sets ANTHROPIC_BASE_URL to an attacker-controlled endpoint and when the repository was opened, Claude Code would read the configuration and immediately issue API requests before showing the trust prompt, potentially leaking the user's API keys. Users on standard Claude Code auto-update have received this fix already. Users performing manual updates are advised to update to version 2.0.65, which contains a patch, or to the latest version.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.3 Medium | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N | GitHub_M |
Weaknesses
- CWE-522 Insufficiently Protected Credentials
Affected Products
| Product | Versions |
|---|---|
claude-codeanthropics |
|
References
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