49/100 CVSS 8.2 🔴 CVE ANALYSISPublished: May 19, 2026

auth-fetch-mcp: SSRF and disk exfiltration via unvalidated auth_fetch and download_media URLs

# SSRF + disk-exfil in `download_media` and `auth_fetch` tools — ymw0407/auth-fetch-mcp ## Severity The `download_media` and `auth_fetch` MCP tools accept arbitrary URLs and reach them as the MCP server process, with `download_media` additionally persisting the fetched response body to a user-controlled output directory. An MCP client (LLM under pr...

8.2

CVSS Score

MEDIUM

Threat Level

Priority /100

TBD

Exploited ITW

Monitor

CISA Status

Sources

🔵

HIGH-PRIORITY SECURITY ADVISORY — Priority Score: 49/100

CVSS 8.2 MEDIUM. SENTINEL APEX recommends immediate patch evaluation. Intelligence from 1 confirmed source(s).

📋 Executive Summary

⚡ Analyst Assessment — SENTINEL APEX v4.0

CYBERDUDEBIVASH SENTINEL APEX has confirmed a MEDIUM-tier threat intelligence signal for GHSA-50c74fa8864bbbc6 affecting npm auth-fetch-mcp. Composite threat score: 49/100. Intelligence corroborated across 1 source(s): github_advisories. CVSS base score: 8.2. Exploitation probability assessed as HIGH based on vulnerability characteristics.

Intelligence sources: github_advisories

⚠️ Business Impact Analysis

⚠️ Privilege escalation — local attacker can become SYSTEM/root
⚠️ Data exfiltration risk — customer and sensitive data at risk

🔗 Attack Chain Analysis

Step-by-step attack chain based on observed TTPs and vulnerability characteristics:

#	Phase	Attacker Action	MITRE
1	Reconnaissance	Attacker identifies exposed auth-fetch-mcp instances via Shodan, Censys, or targeted scanning	`TA0043`
2	Initial Access	Exploitation of GHSA-50c74fa8864bbbc6 in npm auth-fetch-mcp	`T1190`
3	Privilege Escalation	Local privilege escalation to SYSTEM/root for full control	`T1068`
4	Persistence	Backdoor, scheduled task, or new admin account created for persistent access	`T1053`
5	Command & Control	Attacker establishes persistent C2 channel using HTTPS or DNS tunneling	`T1071`
6	Impact / Objectives	Intellectual property theft, espionage, cryptomining, or preparation for future attack stage	`T1657`

⚠ Deep Dive Analysis

This high-severity vulnerability in npm auth-fetch-mcp (CVSS 8.2) represents a significant attack surface. SENTINEL APEX assesses exploitation to be technically feasible with moderate effort. Organizations running auth-fetch-mcp in internet-facing or privileged positions face immediate risk.

SENTINEL APEX URGENCY: HIGH. Score: 49/100 MEDIUM. Patch before exploitation activity begins.

🎯 MITRE ATT&CK Mapping

Category	Mapping
Primary Tactic	Collection
Primary Technique	T1213 — Data from Information Repositories
Sub-Technique	T1190 — Exploit Public-Facing Application
Weakness (CWE)	CWE-918
Intel Type	🔴 CVE ANALYSIS
Source(s)	github_advisories

🔍 Detection Rules — Sigma (SIEM)

Deploy to Splunk, Elastic, Microsoft Sentinel, or QRadar. SOC Pro subscribers receive pre-compiled SIEM-native query packs updated with each pipeline run.

Sigma YAMLtitle: GHSA-50c74fa8864bbbc6 Exploitation Attempt — npm auth-fetch-mcp
id: b457566d1f108a9d-65b0
status: experimental
description: Detects exploitation of GHSA-50c74fa8864bbbc6 in npm auth-fetch-mcp. Priority: MEDIUM. Score: 49/100
author: CYBERDUDEBIVASH SENTINEL APEX v4.0 (bivash@cyberdudebivash.com)
date: 2026-05-19
references:
    - https://nvd.nist.gov/vuln/detail/GHSA-50c74fa8864bbbc6
    - https://blog.cyberdudebivash.in/
tags:
    - attack.initial_access
    - attack.t1190
logsource:
    category: webserver
detection:
    keywords:
        - 'ghsa-50c74fa8864bbbc6'
    condition: keywords
falsepositives:
    - Security scanners
level: high

📡 Detection Rules — YARA (Endpoint)

Deploy to endpoint detection platforms. Enterprise subscribers receive tuned, FP-validated YARA rule packs.

YARArule GHSA_50c74fa8864bbbc6_Exploitation {
    meta:
        description = "Detects artifacts related to GHSA-50c74fa8864bbbc6 exploitation in npm auth-fetch-mcp"
        author      = "CYBERDUDEBIVASH SENTINEL APEX v4.0"
        date        = "2026-05-19"
        severity    = "HIGH"
        cvss        = "8.2"
        priority    = "49/100"
        threat_level = "MEDIUM"
        reference   = "https://nvd.nist.gov/vuln/detail/GHSA-50c74fa8864bbbc6"
    strings:
        $id_str  = "GHSA-50c74fa8864bbbc6" ascii nocase
        $product = "auth_fetch_mcp" ascii nocase wide
    condition:
        any of them
}

🛡️ SOC Response Playbook

1IMMEDIATE (0-1hr): Identify all instances of auth-fetch-mcp in your environment via CMDB/asset inventory
2IMMEDIATE (0-1hr): Apply vendor patch — no maintenance window exception for MEDIUM threats
3IMMEDIATE (1-2hr): If no patch available: implement WAF rules, ACLs, or network-level compensating controls
4SHORT-TERM (2-4hr): Deploy Sigma detection rule to SIEM — validate alert generation in test environment
5SHORT-TERM (4-8hr): Review logs for exploitation indicators (anomalous auth-fetch-mcp requests, error spikes)
6SHORT-TERM (8-24hr): Hunt for post-exploitation: new admin accounts, scheduled tasks, lateral movement
7MONITOR: Subscribe to npm security advisories for patch updates
8ONGOING: Track SENTINEL APEX intelligence feed for follow-on campaigns targeting auth-fetch-mcp

📎 Intelligence References

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Related Resources — SENTINEL APEX

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⚡ CYBERDUDEBIVASH SENTINEL APEX v4.0

Intelligence report generated by CYBERDUDEBIVASH SENTINEL APEX v4.0
Report ID: SENTINEL-GHSA-50c74fa8864bbbc6-2026-05-19 | Priority: 49/100 MEDIUM | Sources: 1
© 2026 CYBERDUDEBIVASH PRIVATE LIMITED
Republication requires written attribution to CYBERDUDEBIVASH SENTINEL APEX

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