{"id":"CVE-2026-96656","published":"2026-09-23T17:17:23Z","modified":"2026-10-21T13:09:18Z","title":"Plex Media Server External Control of File Name or Path Vulnerability","vendor":"Plex","product":"Media Server","tier":"core","eol":null,"description":{"text":"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.","provenance":"source","from":"NVD"},"summary":{"text":"The flaw is an external control of file name or path in Plex Media Server, affecting versions before 1.43.3.10861, where the TranscoderH264Options preference is appended verbatim to x264's option string on every transcode and all .so files are loaded at startup without signature, execute bit, or symbol checks. An attacker with administrator privileges on the server, reachable over the network, can write arbitrary files that may then be executed when loaded, with no user interaction required.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T07:14:57Z"},"cvss":{"score":7.2,"severity":"HIGH","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.01785,"percentile":0.78279,"date":"2026-10-30","provenance":"source"},"kev":{"dateAdded":"2026-10-20","dueDate":"2026-10-23","ransomware":false,"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.","notes":"https://forums.plex.tv/t/important-security-update-for-plex-media-server-v1-43-2-and-earlier/942319 ; ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-96656","provenance":"source"},"vulncheckKev":{"dateAdded":"2026-10-18","exploitedFirstSeen":"2026-10-18","ransomware":false,"evidence":[{"url":"https://www.boredhackerblog.info/2026/10/plex-vulnerabilities-being-exploited-in.html","date":"2026-10-18"},{"url":"https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json","date":"2026-10-20"}],"evidenceTotal":2,"provenance":"source"},"exploited":true,"otx":{"pulseCount":11,"pulses":[{"name":"Actively_Exploited_Kev | Oct 31, 2026","url":"https://otx.alienvault.com/pulse/6ae4aefab0c2191cecd41862","created":"2026-10-30"},{"name":"Actively_Exploited_Kev | Oct 30, 2026","url":"https://otx.alienvault.com/pulse/6ae35d889ea92b4ce19c2680","created":"2026-10-29"},{"name":"Plex vulnerabilities being exploited in the wild to drop a cryptominer","url":"https://otx.alienvault.com/pulse/6ae28367e4148ac8133ccf7a","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Plex vulnerabilities being exploited in the wild to drop a cryptominer","url":"https://otx.alienvault.com/pulse/6ad5b2c95417d4d1ac959070","created":"2026-10-19"}],"provenance":"machine"},"cwes":[{"id":"CWE-73","name":"External Control of File Name or Path"}],"references":[{"url":"https://forums.plex.tv/t/plex-media-server/30447/711","tags":["Release Notes"]},{"url":"https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-266-01.json","tags":["Third Party Advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-96656","tags":["Third Party Advisory","VDB Entry"]},{"url":"https://zmain.info/blog/plex2shell","tags":["Third Party Advisory"]},{"url":"https://www.boredhackerblog.info/2026/10/plex-vulnerabilities-being-exploited-in.html","tags":["Third Party Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-96656","tags":["US Government Resource"]}],"techniques":[{"id":"T1078","name":"Valid Accounts","tactics":["initial-access","persistence","privilege-escalation","stealth"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Requires authenticated admin account access","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"allows an admin user to write arbitrary files","start":38,"end":83}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1059","name":"Command and Scripting Interpreter","tactics":["execution"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: Malicious .so files execute arbitrary code","mappingType":"primary_impact","evidence":[{"from":"description","quote":"may be executed on load","start":89,"end":112}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2026-85370","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-85370","exploited":true,"exploitedSince":"2026-10-20","provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":0,"earliest":"2026-10-18","earliestUrl":"https://github.com/a3igner/plex-codec-cache-implant","repos":[{"name":"a3igner/plex-codec-cache-implant","url":"https://github.com/a3igner/plex-codec-cache-implant","stars":0,"created":"2026-10-18"}]},"first":{"date":"2026-10-18","source":"PoC-in-GitHub","url":"https://github.com/a3igner/plex-codec-cache-implant"},"provenance":"source"},"exploitRefs":[],"flow":[{"stage":"exploitation","techniques":["T1078"],"provenance":"ai"},{"stage":"primary","techniques":["T1059"],"provenance":"ai"}],"timeline":[{"date":"2026-09-23","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-96656","provenance":"source"},{"date":"2026-10-18","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/a3igner/plex-codec-cache-implant","provenance":"source"},{"date":"2026-10-18","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://www.boredhackerblog.info/2026/10/plex-vulnerabilities-being-exploited-in.html","provenance":"source"},{"date":"2026-10-20","kind":"kev","label":"Added to CISA KEV","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2026-10-20","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-85370","provenance":"source"}],"speed":{"daysToPublicExploit":25,"firstExploitFrom":"PoC-in-GitHub","daysToKev":27},"priority":{"score":73.1,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":10.0,"detail":"added 13 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":15.66,"detail":"percentile 0.7828"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":5.0,"detail":"1 PoC-in-GitHub repo"},{"name":"Mentioned in OTX pulses","points":2.45,"detail":"11 pulses"},{"name":"CVSS severity","points":5.04,"detail":"base score 7.2"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}