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High, CVSS 7.4amended

9router: Image prefetch DNS rebinding allows SSRF to internal services

CVE-2026-56676GHSA-cmhj-wh2f-9cgx

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (9router 0.5.2), 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

  • npm 9router

    Affected
    <= 0.4.80
    Fixed in
    0.5.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L
EPSS
  • CVE-2026-56676: 0.19% estimated exploitation activity in the next 30 days; percentile 8.68 (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 9router validates image URLs by resolving the host before fetching, but the later server-side fetch performs a separate DNS resolution. An attacker-controlled DNS name can resolve to a public IP during validation and then rebind to an internal Docker/private IP during the fetch. This allows the server-side image prefetch to reach internal-only HTTP services (SSRF). Details - Affected version / commit: 9router v0.4.80 @ b282f05. - Reachable through /v1/chat/completions with a vision-capable model and an imageurl content part. A vision-capable model name is required so the image survives modality stripping and the server-side prefetch is armed. - The provider used in this reproduction is the bundled mock provider — no real API key and no real provider call. - internal-admin (the SSRF target) is not exposed to the host network; it is reachable only from inside the Docker network. - rebind-dns behaviour for rebind.9r.test: - first A response → 1.1.1.1 (public) to pass the…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-cmhj-wh2f-9cgx

  2. Revision 2 · amended ·

    Amended from osv record GHSA-cmhj-wh2f-9cgx

  3. Revision 1 · created ·

    Published from ghsa record GHSA-cmhj-wh2f-9cgx

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-56676

Advisory: 9router: Image prefetch DNS rebinding allows SSRF to internal services
IDs: CVE-2026-56676, GHSA-cmhj-wh2f-9cgx
Record: https://patchnext.com/advisories/cve-2026-56676 (revision 3, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: 9router 0.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm 9router: affected <= 0.4.80; fixed in 0.5.2

## Suggested inspection (read-only)
- `npm ls 9router --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 9router.
- 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://github.com/advisories/GHSA-cmhj-wh2f-9cgx (GitHub-reviewed advisory GHSA-cmhj-wh2f-9cgx lists affected ranges: npm 9router >=0 <=0.4.80)
- Verified: https://osv.dev/vulnerability/GHSA-cmhj-wh2f-9cgx (OSV record GHSA-cmhj-wh2f-9cgx lists affected ranges: npm 9router >=0 <0.5.2 (fixed))

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