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CVE-2026-21852

MEDIUM CVSS 4.0: 5.3 EPSS 0.03%
Updated Feb 02, 2026
Anthropic
Parameter Value
CVSS 5.3 (MEDIUM)
Affected Versions before 2.0.65
Fixed In 2.0.65
Type CWE-522 (Insufficiently Protected Credentials)
Vendor Anthropic
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
Passive
Minimal interaction

Impact Assessment

Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
Low
Partial disruption

CVSS Vector v4.0

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Anthropic Claude_Code
cpe:2.3:a:anthropic:claude_code:*:*:*:*:*:node.js:*:*
2.0.65