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TI-2021-13235 Aliases CVE-2021-33959GHSA-8788-3qj3-84j7

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

Priority HIGH 72CWE-346Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-346.

Summary

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

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.15035 96th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:plex:media_server:*:*:*:*:*:*:*:*up to 1.21VulnerablePlex
  • cpe:2.3:a:plex:media_server:*:*:*:*:*:*:*:* Versions up to 1.21 Vulnerable ·Plex

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-33959
  2. 2026-10-03 Alias added: GHSA-8788-3qj3-84j7

References

Exploit 2

  • TI-2026-63829 Arbitrary file write in Plex Media Server enables code execution KEVCVSS 4.0HIGH 8.6
  • TI-2020-04669 Deserialization of untrusted data in Plex Media Server KEVCVSS 3.1HIGH 7.2
  • TI-2026-63827 Plex Media Server URL injection lets attackers call other plugins KEVCVSS 4.0MEDIUM 6.9
  • TI-2026-63828 Server-side request forgery in Plex Media Server KEVCVSS 4.0MEDIUM 5.3
  • TI-2026-63826 Server-side request forgery in Plex Media Server KEVCVSS 4.0MEDIUM 5.3
  • TI-2025-42857 Incorrect authorization in Plex Media Server CVSS 3.1HIGH 8.5
See all 18 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences