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5.3
MEDIUM CVSS 4.0
CVE-2026-21852
Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation
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.

INFO

Published Date :

Jan. 21, 2026, 9:16 p.m.

Last Modified :

Jan. 21, 2026, 9:16 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Affected Products

The following products are affected by CVE-2026-21852 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

No affected product recoded yet

: Total Affected Vendor : 0 | Products : 0
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 4.0 MEDIUM [email protected]
Solution
Update Claude Code to version 2.0.65 or later to prevent data exfiltration.
  • Update Claude Code to version 2.0.65.
  • Use the latest version for enhanced security.
  • Avoid opening untrusted repositories.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-21852.

URL Resource
https://github.com/anthropics/claude-code/security/advisories/GHSA-jh7p-qr78-84p7
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-21852 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-21852 weaknesses.

CAPEC-50: Password Recovery Exploitation Password Recovery Exploitation CAPEC-102: Session Sidejacking Session Sidejacking CAPEC-474: Signature Spoofing by Key Theft Signature Spoofing by Key Theft CAPEC-509: Kerberoasting Kerberoasting CAPEC-551: Modify Existing Service Modify Existing Service CAPEC-555: Remote Services with Stolen Credentials Remote Services with Stolen Credentials CAPEC-560: Use of Known Domain Credentials Use of Known Domain Credentials CAPEC-561: Windows Admin Shares with Stolen Credentials Windows Admin Shares with Stolen Credentials CAPEC-600: Credential Stuffing Credential Stuffing CAPEC-644: Use of Captured Hashes (Pass The Hash) Use of Captured Hashes (Pass The Hash) CAPEC-645: Use of Captured Tickets (Pass The Ticket) Use of Captured Tickets (Pass The Ticket) CAPEC-652: Use of Known Kerberos Credentials Use of Known Kerberos Credentials CAPEC-653: Use of Known Operating System Credentials Use of Known Operating System Credentials

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-21852 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-21852 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by [email protected]

    Jan. 21, 2026

    Action Type Old Value New Value
    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.
    Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
    Added CWE CWE-522
    Added Reference https://github.com/anthropics/claude-code/security/advisories/GHSA-jh7p-qr78-84p7
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 5.3
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
VS Confidentiality
VS Integrity
VS Availability
SS Confidentiality
SS Integrity
SS Availability