CVE-2026-96656

High

Plex Media Server External Control of File Name or Path Vulnerability

7.2 CVSS v3.1 CVSS v4.0: 8.6

Published: Sep 23, 2026
Updated: Oct 21, 2026
Vendor: Plex
Affected versions: See affected products
Weakness: CWE-73

Summary

Plex Media Server before 1.43.3.10861 allows an admin user to write arbitrary files that may be executed on load. The preference TranscoderH264Options is appended verbatim to x264’s option string on every transcode. At startup, all .so files are run without signature, execute bit, or symbol checks.

Severity

High (7.2)

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS v4.0 (8.6)

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

Plex Media Server < 1.43.3.10861

Exploitation status

Actively exploited

Listed in the CISA Known Exploited Vulnerabilities catalog on Oct 20, 2026. Federal remediation due: Oct 23, 2026.

Technical details

Technical analysis has not been written for this record yet.

Mitigation & remediation

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.