CVE-2021-33959 in the critical feed json
Plex media server 1.21 and before is vulnerable to ddos reflection attack via plex service.
published 2023-01-18 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-20630
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 15.0%
- EPSS 15.0% chance of exploitation in 30 days, percentile 96%
- public exploits
- 0
- none known
Summary
Plex media server 1.21 and before is vulnerable to ddos reflection attack via plex service.
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 19 mo ago
Exploit prediction
15.04% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- freebuf.com https://www.freebuf.com/articles/web/260338.html referenced PoC, tagged "exploit" by a source, unverified
- github.com https://github.com/lixiang957/CVE-2021-33959 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Classification
- Weakness
-
- CWE-346 Origin Validation Error
References
-
freebuf.com
/articles/web/260338.html
exploit, technical-description, third-party-advisory
-
github.com
/lixiang957/CVE-2021-33959
exploit, third-party-advisory
Sources
- CVE List CVE-2021-33959
- NVD CVE-2021-33959
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.