CVE-2026-21852

Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation

Severity Score

5.3

*CVSS v4

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Attend

*SSVC

Descriptions

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.

Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation

*Credits: N/A

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

None

User Interaction

Passive

System

Vulnerable | Subsequent

Confidentiality

Low

None

Integrity

Low

None

Availability

Low

None

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:Attend

Exploitation

None

Automatable

Yes

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2026-01-05 CVE Reserved
2026-01-21 CVE Published
2026-01-21 CVE Updated
2026-04-21 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-522: Insufficiently Protected Credentials

CAPEC

References (1)

URL	Tag	Source
https://github.com/anthropics/claude-code/security/advisories/GHSA-jh7p-qr78-84p7	X_refsource_confirm

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Anthropics Search vendor "Anthropics"		Claude-code Search vendor "Anthropics" for product "Claude-code"				< 2.0.65 Search vendor "Anthropics" for product "Claude-code" and version " < 2.0.65"		en		Affected