CVE-2026-21852

Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation

Published Jan 21, 2026 CVSS 4.0 · 5.3 Medium EPSS 27.5% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-jh7p-qr78-84p7 Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation
History
Type Values Removed Values Added
First Time appeared Anthropic
Anthropic claude Code
CPEs cpe:2.3:a:anthropic:claude_code:*:*:*:*:*:node.js:*:*
Vendors & Products Anthropic
Anthropic claude Code
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

Type Values Removed Values Added
First Time appeared Anthropics
Anthropics claude Code
Vendors & Products Anthropics
Anthropics claude Code
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation
Weaknesses CWE-522
References
Metrics cvssV4_0

{'score': 5.3, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jan 21, 2026, 9:34 PM
Reserved
Jan 5, 2026, 4:44 PM
Status
Analyzed
Published
Jan 21, 2026, 9:16 PM
Modified
Jun 17, 2026, 10:19 AM