{"id":"CVE-2026-96656","kind":"vulnerability","aliases":["CVE-2026-96656"],"related":[],"title":"Plex Media Server before 1.43.3.10861 allows an admin user to write arbitrary files that may be executed on load","description":"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.\n\nCISA 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.","summary":"An admin user of Plex Media Server can set the TranscoderH264Options preference, which is appended verbatim to x264's options on every transcode, to write arbitrary files. At startup all .so files in the Codecs folder are loaded without signature, execute-bit or symbol checks, so a written file runs as code. CISA lists it as exploited, chained with CVE-2026-96652, -96654 and -96655.","severity":"high","cvss":8.6,"epss":null,"exploited":true,"exploited_at":"2026-10-20T00:00:00+00:00","products":[{"name":"Plex Media Server","fixed":["1.43.3.10861"],"affected":"< 1.43.3.10861","ecosystem":"vendor"},{"name":"Plex Media Server","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["docker","exploited","nas","plex-media-server","rce-chain","self-hosted","vendor"],"not_affected_if":["managed-hosting"],"how_to_check":"In Plex Web: Settings > General, read the server version; anything below 1.43.3.10861 is affected (compare all four numbers). Also look in the Plex Codecs folder for .so/.dll files you did not put there.","fix":"Update Plex Media Server to 1.43.3.10861 or later. On a NAS, download the package from Plex's Downloads page if the package manager is behind. Turn off Remote Access if not needed and do not forward port 32400 directly.","status":"open","published_at":"2026-09-23T17:17:23+00:00","first_seen_at":"2026-10-23T19:11:50+00:00","triaged_at":"2026-10-23T22:39:51+00:00","updated_at":"2026-10-24T00:09:50+00:00","category":"vendor","confidence":0.8,"triage":{"at":"2026-10-23T22:39:51Z","model":"claude-haiku-5-5","output":{"fix":"Apply the vendor mitigation or update per Plex's advisory; the sources do not name a fixed version.\nUnknown which version is affected.","reach":"network","title":"Plex Media Server: admin can write files that run as code","impact":"high","summary":"Plex Media Server lets an admin user write arbitrary files to chosen paths, and some of those files are executed when loaded. It is listed as exploited in the wild and can be chained with CVE-2026-96652, CVE-2026-96654 and CVE-2026-96655.","category":"vendor","who_cares":["plex-media-server","self-hosted"],"confidence":0.6,"needs_auth":"yes","worst_case":"attacker with admin rights runs code on the server","analyst_note":"Find Plex's advisory and the affected/fixed versions and a file-system check; the KEV entry at cisa.gov only gives CISA's required action.","how_to_check":"unknown","needs_analyst":true,"not_affected_if":["managed-hosting"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000503,"input_tokens":3134,"output_tokens":379,"severity_before":"high"},"analyst_status":"done","analyst_note":"Find Plex's advisory and the affected/fixed versions and a file-system check; the KEV entry at cisa.gov only gives CISA's required action.","search":"'-04':175C,201C,232C '-2026':21A,24A,108B,149C,152C,156C '-96652':109B,150C '-96654':110B,153C '-96655':112B,157C '-96656':22A,25A '1.43.3.10861':5A '26':174C,200C,231C 'accord':164C 'action':160C 'adher':228C 'admin':8A,48B,130C 'allow':6A,128C 'append':61B 'appli':161C 'applic':198C 'arbitrari':12A,72B,134C 'asset':222C 'base':179C 'bit':89B 'bod':173C,199C,230C 'chain':42B,105B,146C 'check':92B 'cisa':100B,158C,171C,188C 'cloud':204C 'code':99B 'codec':81B 'complianc':169C 'contain':116C 'control':119C 'cve':20A,23A,107B,148C,151C,155C 'discontinu':207C 'docker':33B 'ensur':168C,227C 'evalu':220C 'everi':68B 'execut':17A,88B,139C 'execute-bit':87B 'exploit':34B,104B 'exposur':225C 'extern':118C 'file':13A,73B,78B,96B,121C,135C 'folder':82B 'follow':197C 'forens':190C 'guidanc':186C,202C 'guidelin':234C 'host':45B 'instruct':167C 'internet':224C 'list':101B 'load':19A,84B,141C 'may':15A,137C 'media':2A,28A,31A,38B,52B,114C 'mitig':162C,213C 'name':122C 'nas':35B 'note':185C,196C 'option':66B 'patch':233C 'path':124C 'plex':1A,27A,30A,37B,51B,113C 'plex-media-serv':36B 'plex2shell':26A 'prefer':58B 'priorit':176C 'product':211C 'rce':41B 'rce-chain':40B 'requir':159C,192C 'respons':218C 'risk':181C 'run':97B 'secur':177C 'see':182C,193C 'self':44B 'self-host':43B 'server':3A,29A,32A,39B,53B,115C 'servic':205C 'set':55B 'signatur':86B 'stakehold':216C 'startup':75B 'symbol':91B 'transcod':69B 'transcoderh264options':57B 'triag':191C 'unavail':215C 'updat':178C 'url':183C,194C 'use':208C 'user':9A,49B,131C 'vendor':46B,166C 'verbatim':62B 'vulner':125C,143C 'without':85B 'write':11A,71B,133C 'written':95B 'x264':64B","nicknames":["Plex2Shell"],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-09-23T17:17:23+00:00","kev":{"dateAdded":"2026-10-20","dueDate":"2026-10-23","requiredAction":"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.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS: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","cvss_by":"9119a7d8-5eab-497f-8521-727c672e3725","poc_count":2,"sources":[{"source":"kev","external_id":"CVE-2026-96656","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-96656","severity":null,"published_at":"2026-10-20T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:50+00:00","fetched_at":"2026-10-25T13:39:28+00:00","note":null},{"source":"analyst","external_id":"CVE-2026-96656:281","url":null,"severity":null,"published_at":"2026-10-23T22:43:00+00:00","modified_at":"2026-10-23T22:43:00+00:00","first_seen_at":"2026-10-23T22:43:00+00:00","fetched_at":"2026-10-23T22:43:00+00:00","note":"CVE record + Plex forum notice: affected < 1.43.3.10861, fixed 1.43.3.10861. Exploited per CISA KEV (Plex2Shell chain). Did not read PoC or social posts; PoC link not saved. Check Point's 1.43.0.10861 looks like a typo."},{"source":"nvd","external_id":"CVE-2026-96656","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-96656","severity":null,"published_at":"2026-09-23T17:17:23+00:00","modified_at":"2026-10-21T13:09:18+00:00","first_seen_at":"2026-10-23T23:44:52+00:00","fetched_at":"2026-10-23T23:44:52+00:00","note":null}],"documents":[{"id":1078,"url":"https://forums.plex.tv/t/important-security-update-for-plex-media-server-v1-43-2-and-earlier/942319","title":"Plex: Important Security Update for Plex Media Server v1.43.2 and earlier","kind":"vendor","source":"analyst","text":null,"published_at":null,"relation":"fix","confidence":null,"note":null},{"id":1577,"url":"https://www.cve.org/CVERecord?id=CVE-2026-96656","title":"CVE Record CVE-2026-96656","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":1575,"url":"https://brandefense.io/knowledge-hub/vulnerabilities/cve-2026-96656/","title":"Brandefense: Plex Media Server arbitrary file write (CVE-2026-96656)","kind":"blog","source":"analyst","text":null,"published_at":null,"relation":"describes","confidence":null,"note":null},{"id":1101,"url":"https://www.cisa.gov/news-events/alerts/2026/10/20/cisa-adds-six-known-exploited-vulnerabilities-catalog","title":"CISA adds six KEVs (Oct 20, 2026)","kind":"advisory","source":"analyst","text":null,"published_at":null,"relation":"advisory","confidence":null,"note":null},{"id":1082,"url":"https://zmain.info/blog/plex2shell","title":"Plex2Shell write-up (Zach Main)","kind":"poc","source":"analyst","text":null,"published_at":null,"relation":"poc","confidence":null,"note":null},{"id":1084,"url":"https://github.com/code-zm/plex2shell","title":"code-zm/plex2shell exploit code","kind":"poc","source":"analyst","text":null,"published_at":null,"relation":"poc","confidence":null,"note":null},{"id":1100,"url":"https://www.bleepingcomputer.com/news/security/cisa-hackers-chain-plex-flaws-in-plex2shell-attacks-to-breach-servers/","title":"CISA: Hackers chain Plex flaws in Plex2Shell attacks to breach servers","kind":"blog","source":"analyst","text":null,"published_at":null,"relation":"mentions","confidence":null,"note":null},{"id":1585,"url":"https://x.com/_master117/status/2113722829476626681","title":"Operator reports NAS compromised by Plex2Shell","kind":"post","source":"analyst","text":"@_master117 (master117, 16926 followers) · likes 0 reposts 0\n@JackRockHardest It's been so rough. My NAS even got compromised by plex2shell. Cleanup was hell","published_at":null,"relation":"discussion","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}