Detections
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SCA: security update for auth-fetch-mcp (GHSA-pvrj-8cg3-j5f8)

high Tenable Self-Hosted Container Security Plugin ID 444223

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - auth-fetch-mcp is an MCP server that lets AI assistants fetch content from authenticated web pages.
 Version 3.0.1 implements SSRF protection in `assertSafeUrl()` (`src/security.ts`) to block requests to
 private and loopback addresses. However, the `isPrivateV6()` function fails to detect IPv4-mapped IPv6
 loopback addresses in their hex-normalized form. When an attacker supplies a URL such as
 `http://[::ffff:127.0.0.1]:PORT/`, the Node.js WHATWG URL parser silently normalizes the host to
 `[::ffff:7f00:1]`. Because `net.isIPv4('7f00:1')` returns `false`, the private-IP check is bypassed and
 the URL is passed to the browser or HTTP client, allowing the MCP tool to reach loopback services that are
 supposed to be blocked. The issue is exploitable under default configuration without any special
 environment variable. Version 3.0.1 patches the issue. (CVE-2026-49857)

Solution

Update the auth-fetch-mcp library and its related packages to version 3.0.2 or later.

See Also

https://github.com/advisories/GHSA-pvrj-8cg3-j5f8

Plugin Details

Severity: High

ID: 444223

Version: Revision 1.3

Type: Local

Family: SCA Checks

Published: 7/1/2026

Updated: 8/14/2026

Supported Sensors: Tenable Cloud Security, Tenable Self-Hosted Container Security

Risk Information

VPR

Risk Factor: Low

Score: 3.3

Percentile: 51.19

Vendor

Vendor Severity: High

CVSS v2

Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:N/A:N

CVSS Score Source: CVE-2026-49857

CVSS v3

Risk Factor: High

Base Score: 7.4

Temporal Score: 6.4

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 7/1/2026

Vulnerability Publication Date: 7/1/2026

Reference Information

CVE: CVE-2026-49857

cwe: CWE-918