CVE-2020-5135

Exp

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.

Published: 2020-10-12 Last update: 2025-10-31 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-5135 is rated Critical Active Threat (99.8/100): CVSS Critical severity, with high exploitation likelihood (EPSS 26.87%, 98th percentile). CISA KEV confirms active exploitation (added 2022-03-15) affecting SonicWall / SonicOS. a weakness (CWE-120) Unauthenticated remote administrative access may be possible. EPSS rose +1.38% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2020-5135

Name: SonicWall SonicOS Buffer Overflow Vulnerability · CISA KEV detail

Exploit added: 2022-03-15

Action due: 2022-04-05

Required action: Apply updates per vendor instructions.

Exploit prediction scoring system (EPSS) score for CVE-2020-5135

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 25.49% 26.87% +1.38%
2 2026-06-10 26.45% 25.49% -0.97%
3 2026-06-05 — 26.45% —

Full EPSS history (47 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-5135

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2020-5135

Affected software / configurations for CVE-2020-5135

Vendor Product Version Raw CPE
sonicwall sonicos <= 6.0.5.3 cpe:2.3:o:sonicwall:sonicos:*:*:*:*:*:*:*:*
sonicwall sonicos >= 6.5.0.0, <= 6.5.1.11 cpe:2.3:o:sonicwall:sonicos:*:*:*:*:*:*:*:*
sonicwall sonicos >= 6.5.4.0, <= 6.5.4.7 cpe:2.3:o:sonicwall:sonicos:*:*:*:*:*:*:*:*
sonicwall sonicos 7.0.0.0 cpe:2.3:o:sonicwall:sonicos:7.0.0.0:*:*:*:*:*:*:*
sonicwall sonicosv <= 6.5.4.4 cpe:2.3:o:sonicwall:sonicosv:*:*:*:*:*:*:*:*

References for CVE-2020-5135

cvelogic Threat Intelligence