CVE-2021-20023: SonicWall Email Security Path Traversal Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 197 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 51.7%
EPSS score, percentile 98.9 of all scored records
- How severe?
- 4.9 Medium
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA deadline 17 Nov 2021. Apply updates per vendor instructions.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 10.0.9 and earlier
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: 17 November 2021.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 10.0.9 and earlier |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
SonicWall Email Security contains a path traversal vulnerability that allows a post-authenticated attacker to read files on the remote host. This vulnerability has known usage in a SonicWall Email Security exploit chain along with CVE-2021-20021 and CVE-2021-20022 to achieve privilege escalation.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2021-20023 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
- CISA marks it as known to be used in ransomware campaigns.
- The due date CISA sets for the required action is 17 Nov 2021.
- The CVE record was published on 20 Apr 2021, 197 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 4.9 (Medium), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 51.7% (percentile 98.9), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 20 Apr 2021 | CVE record published |
| 3 Nov 2021 | Added to CISA KEV |
| 17 Nov 2021 | CISA due date for the required action |
| 1 Oct 2026 | CVE record last updated |
References
More exploited SonicWall vulnerabilities
- CVE-2026-83548: SonicWall SMA1000 Appliances Server-Side Request Forgery Vulnerability
- CVE-2026-83549: SonicWall SMA1000 Appliances OS Command Injection Vulnerability
- CVE-2026-15409: SonicWall SMA1000 Appliances Server-Side Request Forgery Vulnerability
- CVE-2026-15410: SonicWall SMA1000 Appliances Code Injection Vulnerability
- CVE-2025-40602: SonicWall SMA1000 Missing Authorization Vulnerability
- CVE-2023-44221: SonicWall SMA100 Appliances OS Command Injection Vulnerability