Plex is facing a critical security risk due to CVE-2025-34158, an improper input validation vulnerability in its Plex Media Server (PMS) software, affecting versions 1.41.7.x to 1.42.0.x. Despite a patch being released in version 1.42.1, over 314,000 internet-exposed instances remain unpatched, predominantly in the US and Europe. The flaw carries the highest CVSS score, enabling remote exploitation without authentication or user interaction. Successful exploitation could lead to a total loss of confidentiality, integrity, and availability, allowing attackers to access, corrupt, or delete private media data, crash servers, or use compromised systems as footholds for further attacks as seen in the 2022 LastPass breach, where a Plex vulnerability (CVE-2020-5741) facilitated malware deployment on an employee’s device. While no public PoC exploit exists yet, the ease of exploitation and historical abuse of Plex flaws heighten the risk. Users are urged to update immediately and secure access controls to mitigate potential breaches.
Source: https://www.helpnetsecurity.com/2025/08/27/plex-media-server-cve-2025-34158-attack/
TPRM report: https://www.rankiteo.com/company/plex-inc
"id": "ple754082725",
"linkid": "plex-inc",
"type": "Vulnerability",
"date": "6/2020",
"severity": "100",
"impact": "5",
"explanation": "Attack threatening the organization’s existence"{'affected_entities': [{'customers_affected': '314,000+ users with vulnerable '
'instances',
'industry': 'Media/Entertainment Technology',
'location': ['Primarily US and Europe (exposed '
'instances)'],
'name': 'Plex Inc.',
'type': 'Software Company'}],
'attack_vector': ['Network', 'Remote Exploitation'],
'customer_advisories': 'Plex sent direct notifications to users with '
'vulnerable instances.',
'data_breach': {'data_exfiltration': 'Potential (if exploited)',
'file_types_exposed': ['Media files',
'Potential configuration/log files'],
'personally_identifiable_information': 'Possible (if users '
'store PII in media '
'metadata or server '
'logs)',
'sensitivity_of_data': ['Low to High (depends on user-stored '
'content)'],
'type_of_data_compromised': ['Potential: Media files (movies, '
'music, photos)',
'User account data (if stored '
'locally)']},
'date_publicly_disclosed': '2025-08-25',
'description': 'Over 300,000 internet-facing Plex Media Server instances '
'remain vulnerable to CVE-2025-34158, a critical improper '
'input validation vulnerability. The flaw allows remote '
'exploitation without authentication, potentially leading to '
'total loss of confidentiality, integrity, and availability. '
'Plex released a fix in version 1.42.1, but many users have '
'not updated. The vulnerability was flagged by Censys, which '
'observed 314,000 exposed instances as of August 25. '
'Historically, Plex vulnerabilities (e.g., CVE-2020-5741) have '
'been exploited as initial access vectors in high-profile '
'breaches like the 2022 LastPass incident.',
'impact': {'brand_reputation_impact': ['Potential reputational damage for '
'Plex',
'User trust erosion due to unpatched '
'systems'],
'data_compromised': ['Potential unauthorized access to private '
'media/data',
'Risk of data corruption or deletion'],
'downtime': ['Potential server crashes', 'Service unavailability'],
'operational_impact': 'High (risk of total loss of '
'confidentiality, integrity, and '
'availability)',
'systems_affected': '314,000+ Plex Media Server instances '
'(versions 1.41.7.x to 1.42.0.x)'},
'initial_access_broker': {'backdoors_established': 'Potential (if exploited, '
'as seen in LastPass 2022 '
'breach)',
'entry_point': ['Exposed Plex web interface/login '
'portal (versions '
'1.41.7.x–1.42.0.x)'],
'high_value_targets': ['Media servers connected to '
'corporate networks (e.g., '
'employee home devices)']},
'investigation_status': 'Ongoing (vulnerability exposure monitoring by '
'Censys)',
'lessons_learned': ['Critical vulnerabilities in widely used media servers '
'can serve as attack footholds for broader breaches '
'(e.g., LastPass 2022 incident).',
'User inertia in applying patches remains a significant '
'risk factor, even for high-severity flaws.',
"Proactive vendor outreach (e.g., Plex's email campaign) "
'is essential but insufficient without user action.'],
'post_incident_analysis': {'corrective_actions': ['Plex to evaluate forced '
'updates or auto-patching '
'for critical '
'vulnerabilities.',
'Enhanced user education on '
'securing media servers.',
'Collaboration with '
'ISPs/CERTs to notify '
'owners of exposed '
'instances.'],
'root_causes': ['Delayed patch application by '
'end-users despite vendor '
'notifications.',
'Over-exposure of Plex servers to '
'the internet without proper '
'access controls.',
'Lack of automated update '
'mechanisms for some user '
'deployments.']},
'recommendations': ['Immediately update Plex Media Server to version '
'1.42.1.10060 or later.',
'Restrict internet-facing exposure of Plex web '
'interfaces/login portals.',
'Enable multi-factor authentication (MFA) for Plex '
'accounts.',
'Monitor for unusual activity on Plex servers (e.g., '
'unauthorized access attempts).',
'Consider network segmentation to isolate media servers '
'from high-value systems.'],
'references': [{'date_accessed': '2025-08-25', 'source': 'Help Net Security'},
{'date_accessed': '2025-08-25',
'source': 'Censys Research Report'},
{'date_accessed': '2025-08-early',
'source': 'Plex Security Advisory'}],
'response': {'communication_strategy': ['Direct user emails',
'Public advisories via Censys/Help '
'Net Security'],
'containment_measures': ['Urgent patch release (version '
'1.42.1.10060)',
'User email notifications'],
'incident_response_plan_activated': 'Yes (Plex issued security '
'update and user '
'notifications)',
'remediation_measures': ['Patch deployment',
'Securing Plex control panel access'],
'third_party_assistance': ['Censys (vulnerability monitoring)']},
'stakeholder_advisories': 'Plex urged users via email to apply patches; '
'Censys published public warnings.',
'title': 'Critical Vulnerability in Plex Media Server (CVE-2025-34158) '
'Exposes Over 300,000 Instances',
'type': ['Vulnerability Exposure',
'Potential Data Breach',
'Unauthorized Access Risk'],
'vulnerability_exploited': 'CVE-2025-34158 (Improper Input Validation)'}