Plex Media Server Server-Side Request Forgery (SSRF) Vulnerability

🚨SEVERITY: MEDIUM — CVSS 4.3Security Advisory

TL;DR 📌

  • Plex Media Server contains a server-side request forgery (SSRF) vulnerability which could allow an attacker using any X-Plex-Token value to include a full URL in the ‘protocol’ parameter and force the Plex server to POST to the attacker’s chosen destination. This vulnerability can be chained with CVE-2026-96654, CVE-2026-96655, and CVE-2026-96656.
  • Highest CVSS: 4.3 (Medium).
  • Listed in CISA KEV (2026-10-20) — this is being exploited in the wild.
  • Fixed in 1.43.0.10861 — upgrade to this release or later.
  • CVEs: CVE-2026-96652.

What it is

Plex Media Server contains a server-side request forgery (SSRF) vulnerability which could allow an attacker using any X-Plex-Token value to include a full URL in the ‘protocol’ parameter and force the Plex server to POST to the attacker’s chosen destination. This vulnerability can be chained with CVE-2026-96654, CVE-2026-96655, and CVE-2026-96656.

For leadership 🧭

Executive summary. Risk is Medium (CVSS 4.3) across any Plex kit you run. Follow the remediation in the vendor advisory within Immediate — CISA KEV entries carry a federal remediation deadline.

Why it matters:

  • Exposure depends on deployment topology and which access paths reach the affected component.
  • Treat internet-facing and management-plane instances as higher risk than internal-only ones.
  • Keep monitoring for abnormal authentication and configuration events until upgrades complete.

Now / Next / Later:

  • Now: confirm whether you run the affected versions, and check exposure of any that are internet-facing.
  • Next: apply the remediation the advisory specifies, through an approved change window.
  • Later: add a control check so builds cannot drift back onto a vulnerable train.

Source