Vulnerability in Microsoft Windows
CVE-2021-42835
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).
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.012 (66.2th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 66.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- www.plex.tv/media-server-downloads/ (Product, Vendor Advisory)
- bugsec.com/experts_teams/ (Third Party Advisory)
- ir-on.io/2021/12/02/local-privilege-plexcalation/ (Exploit, Third Party Advisory)
- forums.plex.tv/t/security-regarding-cve-2021-42835/761510 (Vendor Advisory)
Frequently asked questions
- What is CVE-2021-42835?
- CVE-2021-42835 is a high-severity vulnerability in Microsoft Windows, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.0/10. Published 2021-12-08.
- How severe is CVE-2021-42835?
- High severity. CVSS v3 base score is 7.0 out of 10.
- Is CVE-2021-42835 known to be exploited?
- 10 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.