How severe is CVE-2020-5135?

CVE-2020-5135 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-5135 being actively exploited?

Yes. CVE-2020-5135 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2022-03-15, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2020-5135?

CVE-2020-5135 primarily affects Sonicwall Sonicos. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-5135?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2020-5135 have an EU (EUVD) identifier?

Yes. CVE-2020-5135 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-26382. It is also flagged as exploited in the EUVD (since 2022-03-15).

When was CVE-2020-5135 published?

CVE-2020-5135 was published on 2020-10-12 and last updated on 2026-06-17.

CVE-2020-5135

CVE-2020-5135 is a critical-severity vulnerability in Sonicwall Sonicos with a CVSS 3.x base score of 9.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2022-03-15). The underlying weakness is classified as CWE-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 27% (98th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2022-03-15)
EU (EUVD) id: EUVD-2020-26382
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2022-03-15)
Weakness: CWE-120
Affected product: Sonicwall Sonicos
Published: 2020-10-12
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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 6.5.4.7, 6.5.1.12, 6.0.5.3, SonicOSv 6.5.4.v and Gen 7 version 7.0.0.0.
How severe is CVE-2020-5135?: CVE-2020-5135 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-5135 being actively exploited?: Yes. CVE-2020-5135 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2022-03-15, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2020-5135?: CVE-2020-5135 primarily affects Sonicwall Sonicos. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-5135?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2020-5135 have an EU (EUVD) identifier?: Yes. CVE-2020-5135 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-26382. It is also flagged as exploited in the EUVD (since 2022-03-15).
When was CVE-2020-5135 published?: CVE-2020-5135 was published on 2020-10-12 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:o:sonicwall:sonicos:*:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sonicos:7.0.0.0:*:*:*:*:*:*:*
cpe:2.3:o:sonicwall:sonicosv:*:*:*:*:*:*:*:*

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