Actively exploited · Published Sep 23, 2026 · Assigned by cisa-cg

CVE-2026-96656Plex Media Server arbitrary file write

High 7.2 Exploited

In plain English

A high-severity security flaw in Media Server from Plex. Attackers are actively exploiting it in the wild (listed by CISA on October 20, 2026). The chance it is exploited in the next 30 days is estimated at 1.8% (higher than 78% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. 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.

Severity (CVSS 3.1)7.2High
Exploit odds (30 days)1.8%top 21.6% of all CVEs
Exploited in the wildYesCISA KEV since Oct 20, 2026
Attack tooling1Public PoC

CISA guidance

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.

Federal agencies must remediate by Oct 23, 2026.

Official description

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.

Affected products (as reported)

VendorProductVersions
Plex Media Server 0 – before 1.43.3.10861

Weakness: CWE-73 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

References