CVE-2021-42835

08.12.2021, 15:15

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).

TOCTOU

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
NIST	NIST	7 HIGH	LOCAL	HIGH	LOW	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
mitre	CNA	---				---
CVE	ADP	---				---

Base Score

CVSS 3.x

EPSS Score

Percentile: 94%

Vendor	Product	Version
plex	media_server	𝑥 < 1.25.0.5282

𝑥

= Vulnerable software versions

Known Exploits!

Common Weakness Enumeration

CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
The software checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the software to perform invalid actions when the resource is in an unexpected state.

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/