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Medium, CVSS 5.5

Unleash: Addon webhook URL is dialed server-side with no internal-address filtering, enabling SSRF to internal services / cloud metadata and exfiltration of configured request headers

CVE-2026-63004GHSA-5vf6-jrqr-78fj

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (unleash-server 8.0.2, 7.6.5, 7.5.2), 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 unleash-server

    Affected
    < 7.5.2>= 7.6.0, < 7.6.5>= 8.0.0, < 8.0.2
    Fixed in
    8.0.2, 7.6.5, 7.5.2

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.5 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
EPSS
  • CVE-2026-63004: 0.39% estimated exploitation activity in the next 30 days; percentile 32.65 (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 Unleash's addon/integration subsystem lets an operator configure a webhook (and the Slack, Microsoft Teams, Datadog, and New Relic integrations) with a target url parameter. Whenever a subscribed feature-flag event fires, the Unleash server itself issues an HTTP request to that configured URL. The URL is taken verbatim from the addon's parameters.url and passed straight to the HTTP client (ky) with no validation of the host: there is no allow-list, no deny-list, and no blocking of loopback, link-local, RFC1918, or cloud-metadata addresses anywhere in the addon code path. A principal able to create or update an addon can therefore point the server at an internal-only URL — for example http://169.254.169.254/latest/meta-data/… (cloud IMDS), http://127.0.0.1:<port/… (a service bound to localhost), or any RFC1918 host — and cause the Unleash server to dial it from inside the trust boundary. The request is blind (the response body is not returned to the caller), but the addon…

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

    Published from ghsa record GHSA-5vf6-jrqr-78fj

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-2026-63004

Advisory: Unleash: Addon webhook URL is dialed server-side with no internal-address filtering, enabling SSRF to internal services / cloud metadata and exfiltration of configured request headers
IDs: CVE-2026-63004, GHSA-5vf6-jrqr-78fj
Record: https://patchnext.com/advisories/cve-2026-63004 (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: unleash-server 8.0.2, 7.6.5, 7.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm unleash-server: affected < 7.5.2; >= 7.6.0, < 7.6.5; >= 8.0.0, < 8.0.2; fixed in 8.0.2, 7.6.5, 7.5.2

## Suggested inspection (read-only)
- `npm ls unleash-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 unleash-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://github.com/advisories/GHSA-5vf6-jrqr-78fj (GitHub-reviewed advisory GHSA-5vf6-jrqr-78fj lists affected ranges: npm unleash-server >=0 =7.6.0 =8.0.0 <8.0.2)

Commands are suggestions: review each one before running it.

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