CVE-2026-42260: Open-WebSearch: SSRF in `fetchWebContent` MCP tool: bracketed IPv6 literals and non-resolving hostname check bypass `isPrivateOrLocalHostname`

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-12 · updated 2026-10-26
Weakness: CWE-918

Description

Open-WebSearch is a multi-engine MCP server, CLI, and local daemon for agent web search and content retrieval. Prior to 2.1.7, isPublicHttpUrl / assertPublicHttpUrl in src/utils/urlSafety.ts do not recognize bracketed IPv6 literals and do not resolve DNS, which combine to allow non-blind SSRF with the response body returned to the caller. This vulnerability is fixed in 2.1.7.

Affected products

Aas-ee open-webSearch: before 2.1.7

References

https://github.com/Aas-ee/open-webSearch/security/advisories/GHSA-v228-72c7-fx8j
https://github.com/Aas-ee/open-webSearch/security/advisories/GHSA-v228-72c7-fx8j

Get alerted when CVE-2026-42260 or the next vulnerability affects your stack