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High, CVSS 8.2amended

open-websearch has SSRF in fetchWebContent MCP tool: bracketed IPv6 literals and non-resolving hostname check bypass isPrivateOrLocalHostname

CVE-2026-42260GHSA-v228-72c7-fx8j

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (open-websearch 2.1.7), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
8.2 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
EPSS
  • CVE-2026-42260: 0.26% estimated exploitation activity in the next 30 days; percentile 17.93 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary src/utils/urlSafety.ts exposes isPublicHttpUrl / assertPublicHttpUrl, used to gate the MCP fetchWebContent tool against private-network targets. The check has two defects that together allow non-blind SSRF with the response body returned to the caller: 1. Bracketed IPv6 literals are never recognized. Node's WHATWG URL.hostname keeps the surrounding […] for IPv6 literals. isIP("[::1]") returns 0 (not 6), so neither isPrivateIpv4 nor isPrivateIpv6 is ever called on an IPv6 literal input — including [::1] itself, and including every IPv4-mapped form such as [::ffff:7f00:1] (= 127.0.0.1 via the IPv4 stack). 2. No DNS resolution. isPrivateOrLocalHostname only inspects the literal hostname string. It never resolves the host to an IP. Any attacker-controlled hostname whose DNS record points at 127.0.0.1 (or any RFC1918 / link-local address) passes the check unchanged, and axios then performs its own resolution and connects to the private address. The isPrivateIpv6 implementation…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-v228-72c7-fx8j

  2. Revision 1 · created ·

    Published from osv record GHSA-v228-72c7-fx8j

Agent brief

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# Patch Next advisory brief: CVE-2026-42260

Advisory: open-websearch has SSRF in `fetchWebContent` MCP tool: bracketed IPv6 literals and non-resolving hostname check bypass `isPrivateOrLocalHostname`
IDs: CVE-2026-42260, GHSA-v228-72c7-fx8j
Record: https://patchnext.com/advisories/cve-2026-42260 (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: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-websearch 2.1.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm open-websearch: affected <= 2.1.6; fixed in 2.1.7

## Suggested inspection (read-only)
- `npm ls open-websearch --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 open-websearch.
- 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-v228-72c7-fx8j (OSV record GHSA-v228-72c7-fx8j lists affected ranges: npm open-websearch >=0 <2.1.7 (fixed))
- Verified: https://github.com/advisories/GHSA-v228-72c7-fx8j (GitHub-reviewed advisory GHSA-v228-72c7-fx8j lists affected ranges: npm open-websearch >=0 <=2.1.6)

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