What is CVE-2020-5135?

CVE-2020-5135 is a critical-severity vulnerability in Sonicwall Sonicos, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2020-10-12.

How severe is CVE-2020-5135?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2020-5135 known to be exploited?

Yes. CVE-2020-5135 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-15), indicating it is being actively exploited. 7 public proof-of-concept repositories are indexed.

Buffer overflow in Sonicwall Sonicos

CVE-2020-5135

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…

Vulnerability class: Buffer Overflow

EPSS: 0.269 (97.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Sonicwall Sonicos — versions SonicOS 6.5.4.7-79n and earlier, 7.0.0.0, SonicOS 6.5.1.11-4n and earlier
Sonicwall Sonicosv

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-03-15. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-04-05.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

PSIRT@sonicwall.com (x_refsource_CONFIRM, Vendor Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2020-5135?: CVE-2020-5135 is a critical-severity vulnerability in Sonicwall Sonicos, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2020-10-12.
How severe is CVE-2020-5135?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2020-5135 known to be exploited?: Yes. CVE-2020-5135 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-15), indicating it is being actively exploited. 7 public proof-of-concept repositories are indexed.