CVE-2020-5135
CriticalExploitedPublic exploitA 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.
Published Oct 12, 2020 · Updated Oct 31, 2025
Key Facts
Patch immediately- CVE-2020-5135 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting SonicOS (Sonicwall), Sonicosv (Sonicwall).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 15, 2022 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 27% probability of exploitation in the next 30 days.
- Fixed versions are available, including SonicOS <=6.0.5.3, Sonicosv <=6.5.4.4, SonicOS 6.0.5.3.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
27%
Higher than 98.0% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2020-5135 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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. This vulnerability affected SonicOS Gen 6 version 6.5.4.7, 6.5.1.12, 6.0.5.3, SonicOSv 6.5.4.v and Gen 7 version 7.0.0.0.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Mar 15, 2022 | Apr 5, 2022 | Known |
| Industry KEV feed | Mar 15, 2022 | Apr 5, 2022 | Known |
| CIRCL KEV | Mar 15, 2022 | Apr 5, 2022 | Not reported |
| ENISA EUVD | Mar 15, 2022 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
4 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| SonicOSSonicwall | 7.0.0.0, >= SonicOS 6.5.4.7-79n and earlier | 6.0.5.3 |
| SonicosvSonicwall | See advisory | 6.5.4.4 |
Patched Releases
SonicOS
<=6.0.5.3
Sonicosv
<=6.5.4.4
Timeline
Publicly disclosed
Oct 12, 2020
Added to CISA KEV
Mar 15, 2022
Added to Industry KEV feed
Mar 15, 2022
Added to CIRCL KEV
Mar 15, 2022
Added to ENISA EUVD
Mar 15, 2022
Last updated
Oct 31, 2025
Weakness Type
- CWE-120 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
References
- advisoryhttps://psirt.global.sonicwall.com/vuln-detail/SNWLID-2020-0010
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: SonicOS (Sonicwall) versions 7.0.0.0, >= SonicOS 6.5.4.7-79n and earlier; Sonicosv (Sonicwall). The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Mar 15, 2022 and is known to be used in ransomware campaigns.
Yes. It was added on Mar 15, 2022 with a federal remediation due date of Apr 5, 2022.
Public exploit code is available.
Fixed versions are available, including SonicOS <=6.0.5.3, Sonicosv <=6.5.4.4, SonicOS 6.0.5.3.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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