Plex Media Server arbitrary file write
Plex Media Server before 1.43.3.10861 lets an admin user write arbitrary files. Fixed in 1.43.3.10861.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Actively exploited
- Fix
- Fixed in 1.43.3.10861
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- 1 proof of concept on GitHub
- Exploitation: active
- Automatable: no
- Technical impact: total
Summary
Plex Media Server, a media streaming application, is affected. An administrator-level user can write arbitrary files to the server, and those files may later be executed when the server loads them, potentially giving the attacker control over the host system.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original 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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: active · Automatable: no · Technical impact: total
- Added to CISA KEV
CISA has evidence of exploitation in the wild
- Record last updated
- CISA remediation deadline
Due date for US federal agencies to patch
Affected versions
- Plex Media Server
fixed in 1.43.3.10861
References 5
forums.plex.tv
cve.org
raw.githubusercontent.com
zmain.info
GitHub · a3igner/plex-codec-cache-implant
Questions about CVE-2026-96656
What does this mean?
An admin user can write arbitrary files on the server, and written files may be executed when loaded, such as unsigned shared objects in the codec directory. The flaw is tied to the TranscoderH264Options preference, which is appended verbatim to x264's option string on every transcode.Source: github.com
Am I affected, and how do I check?
Plex Media Server versions before 1.43.3.10861 are affected. To check, compare the installed Plex Media Server version with 1.43.3.10861.Source: github.com
What should I do about it?
Upgrade Plex Media Server to 1.43.3.10861 or later, which is the version that fixes this issue.Source: github.com
Is it being exploited?
Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-10-20, which means it has evidence of attacks. Public exploit code exists (a proof of concept on GitHub).Source: cisa.gov, cve.now feed data