TC-2026-0105 · NPM · MCP
[email protected]
Verified build of postmark-mcp prior to the 1.0.16 covert BCC injection. Sends email solely to caller-specified recipients via api.postmarkapp.com.
Signed ledger verdict
TC-2026-0105
No known bad (exit 0)
npm:[email protected]
IOC & scope: npm:[email protected] (clean release prior to 1.0.16 BCC backdoor). Verified by human review and signed into the CC-BY 4.0 OSV v1.6.0 feed.
Run live in Counter Workbench
Signed in /feed.json (.sig).
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. Filesystem
Sensitive paths touched:
None observed -
2. Environment
Variables harvested:
POSTMARK_SERVER_TOKEN -
3. Network
Outbound egress domains:
api.postmarkapp.com -
4. Subprocess
Process execution primitives:
None observed -
5. Lifecycle
Install / startup hooks:
None observed -
6. OAuth / MCP
Declared scopes:
email:send -
7. Obfuscation
Encoding / steganography:
None observed -
8. Provenance
Attestation status:
verified_source_diff
Governance & detector mapping
- OWASP Agentic ASI (2026): None triggered (baseline control)
- OWASP Agentic AST (2026): None triggered (baseline control)
- Deterministic rules matched:
Clean baseline control (0 static rules triggered)
Version scoping & related records
- TC-2025-0007 (npm:[email protected]): status
known_bad— First documented malicious MCP server in the wild. Version 1.0.16 injected a covert BCC to [email protected]
Local CLI verification
$ threat-cafe-hook check "npm:[email protected]" [threat.cafe] no_known_bad: npm:[email protected] (TC-2026-0105) Reason: Verified build of postmark-mcp prior to the 1.0.16 covert BCC injection. Sends email solel Source: https://www.npmjs.com/package/postmark-mcp/v/1.0.15 (credited to threat.cafe Baseline Audit)
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-2026-0105",
"modified": "2025-09-27T10:00:00Z",
"published": "2025-09-27T10:00:00Z",
"summary": "Verified build of postmark-mcp prior to the 1.0.16 covert BCC injection. Sends email solely to caller-specified recipients via api.postmarkapp.com.",
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "postmark-mcp"
},
"versions": [
"1.0.15"
]
}
],
"credits": [
{
"name": "threat.cafe Baseline Audit",
"type": "FINDER"
}
],
"references": [
{
"type": "ADVISORY",
"url": "https://www.npmjs.com/package/postmark-mcp/v/1.0.15"
},
{
"type": "WEB",
"url": "https://threat.cafe/incidents/tc-2026-0105/"
}
],
"database_specific": {
"target": "npm:[email protected]",
"kind": "mcp",
"verdict": "no_known_bad",
"ioc": "npm:[email protected] (clean release prior to 1.0.16 BCC backdoor)",
"artifact_sha256": "9212232242f534ec9f75ae1bbdda4b688ca8b06e4274735c1704b73a3eb427df",
"owasp_asi": [],
"owasp_ast": [],
"rules_matched": [],
"abom": {
"fs_sensitive": [],
"env_harvest": [
"POSTMARK_SERVER_TOKEN"
],
"net_egress": [
"api.postmarkapp.com"
],
"proc_exec": [],
"install_hooks": [],
"oauth_scopes": [
"email:send"
],
"obfuscation": [],
"provenance": "verified_source_diff"
},
"license": "CC-BY-4.0",
"record_digest": "sha256:a5469a25ed8c7cdfe0f17ea2fcdfc1e8ade31e1960e6c57beab1984540339dca",
"release_signature_url": "https://threat.cafe/feed.json.sig"
}
}
Have additional IOCs or a maintainer remediation update for TC-2026-0105?
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