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Vulnerability record · CVE-2021-33959 · published 18 January 2023

CVE-2021-33959: Plex media server origin validation error vulnerability

Plex · Media Server

Plex media server 1.21 and before is vulnerable to ddos reflection attack via plex service.

7.5 CVSS 3.1 High EPSS 15% · top 3.4% CWE-346 · Origin validation error
7.5CVSS 3.1 base score
15%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 4 tagged exploit
17 Jun 2026Last modified by NVD

Description

Plex media server 1.21 and before is vulnerable to ddos reflection attack via plex service.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/lixiang957/CVE-2021-33959 ExploitThird Party Advisory
https://www.freebuf.com/articles/web/260338.html ExploitTechnical DescriptionThird Party Advisory
https://github.com/lixiang957/CVE-2021-33959 ExploitThird Party Advisory
https://www.freebuf.com/articles/web/260338.html ExploitTechnical DescriptionThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.2CVE-2020-5741Plex Media Server Windows deserialization leads to Python code executionPlex Media Server on Windows deserializes untrusted data, allowing a remote, authenticated attacker to execute arbitrary Python code. The flaw is a C…KEVEPSS 73%analysed9.8CVE-2018-13415Plex media server xml external entity (xxe) vulnerabilityIn Plex Media Server 1.13.2.5154, the XML parsing engine for SSDP/UPnP functionality is vulnerable to an XML External Entity Processing (XXE) attack.…EPSS 32%8.8CVE-2020-5742Plex media server vulnerabilityImproper Access Control in Plex Media Server prior to June 15, 2020 allows any origin to execute cross-origin application requests.EPSS 1.4%8.8CVE-2019-19141Plex media server path traversal vulnerabilityThe Camera Upload functionality in Plex Media Server through 1.18.2.2029 allows remote authenticated users to write files anywhere the user account r…EPSS 4.7%7.8CVE-2020-5740Plex media server uncontrolled search path element vulnerabilityImproper Input Validation in Plex Media Server on Windows allows a local, unauthenticated attacker to execute arbitrary Python code with SYSTEM privi…EPSS 0.75%7.5CVE-2014-9304Plex media server permissions and access controls vulnerabilityPlex Media Server before 0.9.9.3 allows remote attackers to bypass the web server whitelist, conduct SSRF attacks, and execute arbitrary administrati…EPSS 8.1%7.1CVE-2025-69414Plex media server incorrect authorization vulnerabilityPlex Media Server (PMS) through 1.42.2.10156 allows retrieval of a permanent access token via a /myplex/account call with a transient access token.EPSS 0.25%7.1CVE-2025-69415Plex media server vulnerabilityIn Plex Media Server (PMS) through 1.42.2.10156, ability to access /myplex/account with a device token is not properly aligned with whether the devic…EPSS 0.29%

Source: NIST National Vulnerability Database (record CVE-2021-33959), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.