Exploited vulnerability · CISA KEV

Is CVE-2020-5135 exploited? Yes: in CISA KEV since 15 Mar 2022

Gociux · SonicWall SonicOS · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2020-5135, SonicWall SonicOS Buffer Overflow Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 15 Mar 2022, 519 days after it was published. It is known to be used in ransomware campaigns. It affects SonicWall SonicOS, an internet-facing product of the kind attackers use for initial access. If you run it, CISA's required action is: Apply updates per vendor instructions.

What it is

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.

What to do

1. Check whether you run it. Look for SonicOS in your asset inventory, including appliances and cloud images. Stack check lists every exploited SonicWall CVE at once.
2. Apply the fix. Apply updates per vendor instructions.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 12 Oct 2020.
4. Get told next time. Email alerts when CISA adds a CVE for SonicWall.

Other exploited CVEs in SonicOS

• CVE-2024-53704: SonicWall SonicOS SSLVPN Improper Authentication Vulnerability (18 Feb 2025)
• CVE-2024-40766: SonicWall SonicOS Improper Access Control Vulnerability (9 Sep 2024)

References

• nvd.nist.gov/vuln/detail/CVE-2020-5135

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in March 2022 · SonicWall scorecard · act-now radar.