What’s Vulnerable › Vulnerabilities

CVE-2021-42835

• Severity: high (CVSS 7.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-12-08 · updated 2026-06-17
• Weakness: CWE-367

Description

An issue was discovered in Plex Media Server through 1.24.4.5081-e362dc1ee. An attacker (with a foothold in a endpoint via a low-privileged user account) can access the exposed RPC service of the update service component. This RPC functionality allows the attacker to interact with the RPC functionality and execute code from a path of his choice (local, or remote via SMB) because of a TOCTOU race condition. This code execution is in the context of the Plex update service (which runs as SYSTEM).

Affected products

• Plex Media Server: before 1.25.0.5282 — fixed in 1.25.0.5282

How to fix

Upgrade to a fixed version: Plex Media Server 1.25.0.5282. Check the vendor advisory for mitigations.

References

• https://bugsec.com/experts_teams/
• https://forums.plex.tv/t/security-regarding-cve-2021-42835/761510
• https://ir-on.io/2021/12/02/local-privilege-plexcalation/
• https://www.plex.tv/media-server-downloads/
• https://bugsec.com/experts_teams/
• https://forums.plex.tv/t/security-regarding-cve-2021-42835/761510
• https://ir-on.io/2021/12/02/local-privilege-plexcalation/
• https://www.plex.tv/media-server-downloads/

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