TC-2026-0017 · GH · PACKAGE

anthropics/[email protected]

CVE-2026-21852 (CVSS 5.3): repository .claude/settings.json could override ANTHROPIC_BASE_URL before trust confirmation, exfiltrating ANTHROPIC_API_KEY and workspace prompts to an attacker proxy.

Primary advisory (Check Point Research) Back to all 66 records

Signed ledger verdict

TC-2026-0017
Known bad (exit 2) gh:anthropics/[email protected]

IOC & scope: gh:anthropics/[email protected] (CVE-2026-21852). Verified by human review and signed into the CC-BY 4.0 OSV v1.6.0 feed.

Credited finder
Check Point Research ↗
Recorded timestamp
2026-01-28
Canonical SHA-256
77849796fe9a1473…
Local hook action
Block (exit 2)
Run live in Counter Workbench

Signed in /feed.json (.sig).

01 8-Vector Capability X-Ray (ABOM) & OWASP Agentic Crosswalk

Deterministic capability profile and taxonomy mapping.

Every artifact in the threat.cafe ledger is profiled across eight execution vectors and mapped to the OWASP Top 10 for Agentic Applications (ASI01-ASI10) and Agentic Skills & Tools (AST01-AST10).

8-Vector Capability X-Ray (ABOM)

  1. 1. Filesystem
    Sensitive paths touched: .claude/settings.json
  2. 2. Environment
    Variables harvested: ANTHROPIC_API_KEY, ANTHROPIC_BASE_URL
  3. 3. Network
    Outbound egress domains: attacker-anthropic-proxy.invalid:443
  4. 4. Subprocess
    Process execution primitives: None observed
  5. 5. Lifecycle
    Install / startup hooks: None observed
  6. 6. OAuth / MCP
    Declared scopes: None observed
  7. 7. Obfuscation
    Encoding / steganography: None observed
  8. 8. Provenance
    Attestation status: vulnerable_release_cve_2026_21852

Governance & detector mapping

  1. OWASP Agentic ASI (2026): ASI03 (Identity & Privilege Abuse), ASI04 (Agentic Supply Chain Vulnerabilities)
  2. OWASP Agentic AST (2026): AST02 (Tool & Skill Injection), AST04 (Covert Channel Exfiltration)
  3. Deterministic rules matched: CONFIG_05_REPO_HOOK_RCE

Version scoping & related records

Local CLI verification

$ threat-cafe-hook check "gh:anthropics/[email protected]"
[threat.cafe] known_bad: gh:anthropics/[email protected] (TC-2026-0017)
  Reason: CVE-2026-21852 (CVSS 5.3): repository .claude/settings.json could override ANTHROPIC_BASE_
  Source: https://nvd.nist.gov/vuln/detail/CVE-2026-21852 (credited to Check Point Research)

OSV v1.6.0 machine-readable record

Included in /feed.json under CC-BY 4.0 license and verified by /feed.json.sig.

{
  "schema_version": "1.6.0",
  "id": "TC-2026-0017",
  "modified": "2026-01-28T16:00:00Z",
  "published": "2026-01-28T16:00:00Z",
  "summary": "CVE-2026-21852 (CVSS 5.3): repository .claude/settings.json could override ANTHROPIC_BASE_URL before trust confirmation, exfiltrating ANTHROPIC_API_KEY and workspace prompts to an attacker proxy.",
  "affected": [
    {
      "package": {
        "ecosystem": "gh",
        "name": "anthropics/claude-code"
      },
      "versions": [
        "1.0.52"
      ]
    }
  ],
  "credits": [
    {
      "name": "Check Point Research",
      "type": "FINDER"
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-21852"
    },
    {
      "type": "WEB",
      "url": "https://threat.cafe/incidents/tc-2026-0017/"
    }
  ],
  "database_specific": {
    "target": "gh:anthropics/[email protected]",
    "kind": "package",
    "verdict": "known_bad",
    "ioc": "gh:anthropics/[email protected] (CVE-2026-21852)",
    "artifact_sha256": "77849796fe9a14738b232f24922c21926d1835256017df014e66556b63022b29",
    "owasp_asi": [
      "ASI03",
      "ASI04"
    ],
    "owasp_ast": [
      "AST02",
      "AST04"
    ],
    "rules_matched": [
      "CONFIG_05_REPO_HOOK_RCE"
    ],
    "abom": {
      "fs_sensitive": [
        ".claude/settings.json"
      ],
      "env_harvest": [
        "ANTHROPIC_API_KEY",
        "ANTHROPIC_BASE_URL"
      ],
      "net_egress": [
        "attacker-anthropic-proxy.invalid:443"
      ],
      "proc_exec": [],
      "install_hooks": [],
      "oauth_scopes": [],
      "obfuscation": [],
      "provenance": "vulnerable_release_cve_2026_21852"
    },
    "license": "CC-BY-4.0",
    "record_digest": "sha256:3fb0a80a3c5ae0a2c75d354304754a3c296c2b9f4b83082376407e63613fdf5e",
    "release_signature_url": "https://threat.cafe/feed.json.sig"
  }
}

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