Apify Model Context Protocol (MCP) server: Domain Allowlist Bypass in fetch-apify-docs via String Prefix Matching

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2026-46341: 0.23% estimated exploitation activity in the next 30 days; percentile 14.44 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The fetch-apify-docs tool validates URLs against a domain allowlist using String.startsWith() instead of proper URL hostname comparison. This allows bypass via attacker-controlled subdomains (e.g., https://docs.apify.com.evil.com/), enabling the tool to fetch and return arbitrary web content to the LLM. Details Vulnerable component src/tools/common/fetchapifydocs.ts, line 51: src/const.ts, lines 167-170: How the bypass works String.startsWith('https://docs.apify.com') matches any string beginning with that prefix, including: - https://docs.apify.com.evil.com/payload - attacker-controlled subdomain - https://docs.apify.com@evil.com/payload - userinfo component in URL (browser behavior varies, but fetch() in Node.js may follow this) - https://docs.apify.com.evil.com:8080/path - custom port on attacker domain All of these pass the startsWith check because they begin with the exact string https://docs.apify.com. The fetched content is returned to the LLM After the allowlist check…

Published by the source

19 May 2026, 16:34 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 12:52 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-jwp7-wg77-3w9v

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-jwp7-wg77-3w9v

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# Patch Next advisory brief: CVE-2026-46341

Advisory: Apify Model Context Protocol (MCP) server: Domain Allowlist Bypass in fetch-apify-docs via String Prefix Matching
IDs: CVE-2026-46341, GHSA-jwp7-wg77-3w9v
Record: https://patchnext.com/advisories/cve-2026-46341 (revision 2, source checked 26 Oct 2026, 12:52 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @apify/actors-mcp-server 0.9.21. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @apify/actors-mcp-server: affected < 0.9.21; fixed in 0.9.21

## Suggested inspection (read-only)
- `npm ls @apify/actors-mcp-server --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @apify/actors-mcp-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-jwp7-wg77-3w9v (OSV record GHSA-jwp7-wg77-3w9v lists affected ranges: npm @apify/actors-mcp-server >=0 <0.9.21 (fixed))
- Verified: https://github.com/advisories/GHSA-jwp7-wg77-3w9v (GitHub-reviewed advisory GHSA-jwp7-wg77-3w9v lists affected ranges: npm @apify/actors-mcp-server >=0 <0.9.21)

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