CVERadar
HIGH · CVSS 4.0 8.6CISA KEV · added 2026-10-20EPSS 0.82% (p57)Threat level 58

CVE-2026-96656: Plex Media Server External Control of File Name or Path Vulnerability

Plex · Media Server · NVD published 2026-09-23 · posted 2026-10-21 · last modified 2026-10-21

What it is

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.

WeaknessCWE-73
CVSS vectorCVSS: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 (source: 9119a7d8-5eab-497f-8521-727c672e3725)
CISA due date2026-10-23 (for US federal agencies under BOD; a good deadline for everyone)
ATT&CK tacticsn/a

Step-by-step fix guide: How to fix CVE-2026-96656: Plex Media Server (exploited in the wild)

Exploitation evidence

First exploit evidence seen: 2026-10-20 (earliest date across the sources below).

Exploited in the wild

  • CISA KEV: listed since 2026-10-20. Source

Public exploit code

GitHub proof-of-concept repositories below quality bar

1 public repositories from 1 accounts, first seen 2026-10-18.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: CISA KEV · nomi-sec/PoC-in-GitHub.

No ATT&CK techniques could be mapped or inferred for this CVE yet.

How to fix it

CISA required action

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. (source: CISA KEV)

Fixed versions

  • plex media server: upgrade to 1.43.3.10861 or later

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

Detection Generic guidance

    Response checklist Generic guidance

    1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
    2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
    3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
    4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.

    Sources