How severe is CVE-2021-20023?

CVE-2021-20023 has a CVSS score of 4.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-20023?

Affected package information for CVE-2021-20023 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2021-20023?

No fixed version has been published for CVE-2021-20023 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2021-20023 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2021-20023, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-20023?

CVE-2021-20023 has an EPSS (Exploit Prediction Scoring System) score of 55.4%, placing it in the 98th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2021-20023 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2021-20023 (SonicWall Email Security Path Traversal Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03. CISA required all US federal civilian agencies to remediate this vulnerability by 2021-11-17. The required action was: Apply updates per vendor instructions. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2021-20023?

CVE-2021-20023 is classified as Path Traversal (CWE-22). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2021-20023?

CVE-2021-20023 affects sonicwall email security; sonicwall email security appliance 3300 firmware; sonicwall email security appliance 4300 firmware; sonicwall email security appliance 5000 firmware, and 7 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2021-20023 published, and has it been updated?

CVE-2021-20023 was published on April 20, 2021 and was last updated on November 12, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2021-11-03 — agencies required to remediate by 2021-11-17 · Ransomware

CVE-2021-20023

MEDIUM

SonicWall Email Security version 10.0.9.x contains a vulnerability that allows a post-authenticated attacker to read an arbitrary file on the remote host.

Published

Apr 20, 2021

Updated

Nov 12, 2025

Affected

0 pkgs

Patched

None yet

Exploits

2 known

EPSS Exploitation Probability

via FIRST.org ↗

55.4%probability of exploitation in next 30 days

High Risk98th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

SonicWall Email Security version 10.0.9.x contains a vulnerability that allows a post-authenticated attacker to read an arbitrary file on the remote host.

Affected Products

11 products · 11 configurations

Application

email securitysonicwall

< 10.0.9.6173

range

email security appliance 3300 firmwaresonicwall

< 10.0.9.6177

range

email security appliance 4300 firmwaresonicwall

< 10.0.9.6177

range

email security appliance 5000 firmwaresonicwall

< 10.0.9.6177

range

email security appliance 5050 firmwaresonicwall

< 10.0.9.6177

range

email security appliance 7000 firmwaresonicwall

< 10.0.9.6177

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

SonicWall Email Security version 10.0.9.x contains a vulnerability that …

cisa.govCISANov 2021

SonicWall Email Security version 10.0.9.x contains a vulnerability that …

sonicwall.comAPIApr 2021

Frequently Asked Questions

SonicWall Email Security version 10.0.9.x contains a vulnerability that allows a post-authenticated attacker to read an arbitrary file on the remote host.

O3 Security · Impact-Aware SCA

Is CVE-2021-20023 in your stack?

O3 detects CVE-2021-20023 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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