CVE-2020-5135: in the CISA KEV catalogue
SonicWall SonicOS Buffer Overflow Vulnerability. CISA added CVE-2020-5135 to the Known Exploited Vulnerabilities catalogue on 2022-03-15 with a default due date of 2022-04-05. Known ransomware campaign use: Known. Forensic triage flag: No.
A buffer overflow vulnerability in SonicOS allows a remote attacker to cause Denial of Service (DoS) and potentially execute arbitrary code by sending a malicious request to the firewall. (CISA description)
- Vendor / product
- SonicWall SonicOS
- CWE
- CWE-120
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 27%, percentile 98 (scored 2026-11-03)
EPSS puts about 27 in 100 odds (27%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 98% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2020-5135 in the CISA KEV catalogue?
Yes. CISA added CVE-2020-5135 (SonicWall SonicOS Buffer Overflow Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2022-03-15. CISA's default due date for it is 2022-04-05.
Is CVE-2020-5135 used in ransomware attacks?
CISA marks known ransomware campaign use as Known for CVE-2020-5135.
What should I do about CVE-2020-5135?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2020-5135