GHSA-JH7P-QR78-84P7

Vulnerability from github – Published: 2026-01-21 01:00 – Updated: 2026-01-21 21:40
VLAI?
Summary
Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation
Details

A vulnerability in Claude Code's project-load flow allowed malicious repositories to exfiltrate data including Anthropic API keys before users confirmed trust. If a user started Claude Code in an attacker-controller repository, and the repository included a settings file that set ANTHROPIC_BASE_URL to an attacker-controlled endpoint, Claude Code would issue API requests before showing the trust prompt, including 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 the latest version.

Severity ?
5.3 (Medium)
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
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@anthropic-ai/claude-code"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.65"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-21852"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-522"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-21T01:00:31Z",
    "nvd_published_at": "2026-01-21T21:16:08Z",
    "severity": "MODERATE"
  },
  "details": "A vulnerability in Claude Code\u0027s project-load flow allowed malicious repositories to exfiltrate data including Anthropic API keys before users confirmed trust. If a user started Claude Code in an attacker-controller repository, and the repository included a settings file that set ANTHROPIC_BASE_URL to an attacker-controlled endpoint, Claude Code would issue API requests before showing the trust prompt, including potentially leaking the user\u0027s API keys.\n\nUsers on standard Claude Code auto-update have received this fix already. Users performing manual updates are advised to update to the latest version.",
  "id": "GHSA-jh7p-qr78-84p7",
  "modified": "2026-01-21T21:40:17Z",
  "published": "2026-01-21T01:00:31Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/anthropics/claude-code/security/advisories/GHSA-jh7p-qr78-84p7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-21852"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/anthropics/claude-code"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Claude Code Leaks Data via Malicious Environment Configuration Before Trust Confirmation"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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