CVE-2026-96656
CVE-2026-96656 is a security flaw in Plex Media Server, software for streaming your own films and music around the house. Attackers are using a flaw in Plex Media Server. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 20 Oct 2026.[1]
Plex Media Server is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Fixed in version 1.43.3.10861 of Media Server.
Description
CISA calls it an external control of file name or path in Plex Media Server. In its words: “Plex Media Server contains an external control of file name or path vulnerability which can allow an admin user to write arbitrary files that may be executed on load. This vulnerability can be chained with CVE-2026-96652, CVE-2026-96654, and CVE-2026-96655.”[1]
The CVE record adds: “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.”[2]
The underlying weakness is CWE-73, in MITRE’s list of common software weaknesses.
It scores 7.2 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| Media Server | 1.43.3.10861 |
Every device with Plex Media Server needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 20 Oct 2026, 27 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 23 Oct 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 2%. That’s in the top 22% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Plex has published a fix or advice.[3] CISA’s 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).”[1]
- Update Plex Media Server now.Install the latest update from Plex on every device that has it, and restart when asked. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on 1.43.3.10861 or later.Fixed in version 1.43.3.10861 of Media Server. Anything older is what attackers are going after.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.2.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 2%.[4] |
See also
Other Plex Media Server flaws
- CVE-2026-96655: server-side request forgery (SSRF) ·
- CVE-2026-96654: improper neutralization of encoded URI schemes in a web page ·
- CVE-2026-96652: server-side request forgery (SSRF) ·
- CVE-2020-5741: remote code execution ·
Similar flaws
- CVE-2025-33053, Microsoft Windows: external control of file name or path ·
- CVE-2025-24054, Microsoft Windows: NTLM hash disclosure spoofing ·
- CVE-2025-0111, Palo Alto Networks PAN-OS: file read ·
- CVE-2024-43451, Microsoft Windows: nTLMv2 hash disclosure spoofing ·
Added the same day
- CVE-2026-96655, Plex Media Server: server-side request forgery (SSRF) ·
- CVE-2026-96654, Plex Media Server: improper neutralization of encoded URI schemes in a web page ·
- CVE-2026-96652, Plex Media Server: server-side request forgery (SSRF) ·
- CVE-2026-110936, Siemens Software Center: uncontrolled search path element ·
- CVE-2026-106931, EG Secure Solutions SiteGuard Server Edition: OS command injection ·
Every Plex flaw on CISA’s list · Everything added in October 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Plex Media Server External Control of File Name or Path Vulnerability”. Known Exploited Vulnerabilities Catalog, added 20 Oct 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-96656 Detail”. National Vulnerability Database, published 23 Sep 2026.
- ^ Plex. Advisories and fixes: forums.plex.tv, forums.plex.tv.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.018, percentile 78.3, 31 Oct 2026.
- CVE Program. “CVE-2026-96656”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.