CVE-2021-33720A vulnerability has been identified in SIPROTEC 5 relays with CPU variants CP050 (All versions < V8.80), SIPROTEC 5 relays with CPU…
- 7.5HighCVSS base score
- 1.0%Exploitation in 30 daysEPSS · top 36% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
A vulnerability has been identified in SIPROTEC 5 relays with CPU variants CP050 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP100 (All versions < V8.80), SIPROTEC 5 relays with CPU variants CP300 (All versions < V8.80). Specially crafted packets sent to port 4443/tcp could cause a Denial-of-Service condition.
Timeline
ID reserved
By siemens
- 4 months later
· 4 months later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 1.0% · top 36% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
Siemens · SIPROTEC 5 relays with CPU variants CP050
- affected All versions < V8.80
Siemens · SIPROTEC 5 relays with CPU variants CP100
- affected All versions < V8.80
Siemens · SIPROTEC 5 relays with CPU variants CP300
- affected All versions < V8.80
References
References1
- https://cert-portal.siemens.com/productcert/pdf/ssa-847986.pdf (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-20397 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-33720)Record last updated .