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 :
June 17, 2026, 10:19 a.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.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Claude Code to version 2.0.65.
- Use the latest version for enhanced security.
- Avoid opening untrusted repositories.
Public PoC/Exploit Available at Github
CVE-2026-21852 has a 80 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
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 | Vendor Advisory |
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.
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).
None
HTML Ruby JavaScript Shell
Agent memory forensics — trace a bad agent action back to the exact poisoned memory, see the blast radius, roll it back
ai-agents dfir forensics incident-response llm-security mcp memory prompt-injection provenance tamper-evident
Makefile Python
Claude-only agent framework
Shell
Curated security auditors for the backend stack — Supabase, Firebase, Hasura, Strapi, Directus, Payload, Convex, n8n, Ollama & more. Keyless, active-probe, MIT.
awesome awesome-list baas backend devsecops graphql headless-cms security security-audit vulnerability-scanner
Scan a repo's .claude/ config (settings.json hooks, MCP servers, env, allowed-tools) for the RCE & API-key-exfiltration footguns (CVE-2025-59536, CVE-2026-21852) that fire when you clone+open an untrusted repository. Static, zero-dep, local-first.
ai-agents claude claude-code cve devsecops mcp rce security static-analysis supply-chain-security
JavaScript
None
Dockerfile Shell Go
None
Batchfile Shell Python JavaScript HTML
Deep architectural audit and competitive analysis of AI agentic CLI coding tools: Claude Code, OpenCode, Hermes Agent, Kilo Code / Roo Code. Strengths, weaknesses, failure modes, missing features, and white-space opportunity assessment.
Active red-teaming for MCP servers. Source analysis + live exploitation + auto-fix. Claude Code plugin.
HTML Shell Python
NetSecAudit AI — Claude AI 驅動的防禦性資安掃描平台
Python JavaScript HTML CSS
None
JavaScript TypeScript
None
Dockerfile Python HTML
None
Jinja Shell PowerShell Dockerfile
None
Python TypeScript TeX Makefile Shell
A hardening pack for Claude Code. REF: affaan-m/ECC.
JavaScript PowerShell Shell
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.
-
TheCyberThrone
Claude Code Security vs. OpenAI Codex Security – AI Arms Race
A Technical Comparison for AppSec Engineers | March 2026TL;DRBoth tools launched within two weeks of each other in early 2026. Both use LLM-driven reasoning to find and patch vulnerabilities beyond wh ... Read more
-
CybersecurityNews
Claude Code Hacked to Achieve Full RCE and Hijacked Organization API keys
Claude Code Hacked RCE Hijacked Organization API keys Critical vulnerabilities in Anthropic’s Claude Code, an AI-powered command-line development tool. The flaws could allow attackers to achieve Remot ... Read more
-
CybersecurityNews
Critical Claude Code Vulnerabilities Enables Remote Code Execution Attacks
Claude Code Vulnerabilities A critical security flaw in Anthropic’s Claude Code demonstrates how threat actors can exploit repository configuration files to execute malicious code and steal sensitive ... Read more
-
The Register
Claude collaboration tools left the door wide open to remote code execution
Security vulnerabilities in Claude Code could have allowed attackers to remotely execute code on users' machines and steal API keys by injecting malicious configurations into repositories, and then wa ... Read more
-
The Hacker News
Claude Code Flaws Allow Remote Code Execution and API Key Exfiltration
Cybersecurity researchers have disclosed multiple security vulnerabilities in Anthropic's Claude Code, an artificial intelligence (AI)-powered coding assistant, that could result in remote code execut ... Read more
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.
-
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'anthropics', 'product': 'claude-code', 'versions': [{'status': 'affected', 'version': '< 2.0.65'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-21852', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-01-21T21:34:19.798222Z'} -
Initial Analysis by [email protected]
Feb. 02, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Added CPE Configuration OR *cpe:2.3:a:anthropic:claude_code:*:*:*:*:*:node.js:*:* versions up to (excluding) 2.0.65 Added Reference Type GitHub, Inc.: https://github.com/anthropics/claude-code/security/advisories/GHSA-jh7p-qr78-84p7 Types: Vendor Advisory -
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