CVE-2021-42835
No known exploitation. EPSS puts it in the 66th percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
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).
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
1.2% chance of exploitation activity in the next 30 days, which ranks it in the 66th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
7 events over 1660 days, from the signal feeds we watch.
- OpenVAS check added
- EPSS band changemoderate → low
- Patch availablerecord updated
- Publishedweakness classified, att&ck mapped
Affected products
And 1 more affected product. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Scored 7.0 by NVD.
How it is reached
- Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
- Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
- Privileges Required LowRequires basic user-level privileges
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality HighTotal information disclosure — all data in the component is compromised
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
- Privilege EscalationT1068Exploitation for Privilege Escalationmedium confidence
Sources
References in the record
- plex.tv/media-server-downloads/
- bugsec.com/experts_teams/
- ir-on.io/2021/12/02/local-privilege-plexcalation/
And 1 more reference. See all after sign-in
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