Plex Media Server - RCE (CVE-2026-96656)
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.
psychologyCrowdSec Analysis
CVE-2026-96656 is a code execution vulnerability in Plex Media Server before 1.43.3.10861. An administrator-level attacker can set the hidden TranscoderH264Options preference, which is passed verbatim to x264, to write an arbitrary file; Plex then loads every shared object in its codecs directory at startup without any check. It is the final step of the Plex2Shell exploitation chain, which obtains the admin token through earlier vulnerabilities.
CrowdSec has been tracking this vulnerability and its exploits since 28th of October 2026.
CrowdSec has not observed any significant exploitation activity targeting CVE-2026-96656 across its network. As a result, no community-driven trend analysis is available for this vulnerability at this time.
Attackers send PUT /:/prefs requests that set the TranscoderH264Options query parameter to an x264 option string using dump-yuv to write a .so file, which Plex loads on its next start.
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| Event | Date |
|---|---|
| CVE Published | 2026-09-23 |
| CISA KEV | 2026-10-20 |
| CISA Remediation Deadline | 2026-10-23 |
| Rule Released | 2026-10-28 |