CVE-2021-20023
KEVRansomware UseSonicWall Email Security Path Traversal Vulnerability
Description
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.
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.
CVSS 3.1 vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:NPublishedApr 20, 2021
Last modifiedOct 1, 2026
Added to KEVNov 3, 2021
Remediation dueNov 17, 2021
References
- psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0010Vendor Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20023US Government Resource
0 recent articles mention this CVE
70
Risk assessment · High
Actively exploited and used by ransomware crews. Patch immediately.
- Exploitation
- Confirmed in the wild (CISA KEV)
- Federal remediation deadline
- Overdue by 1805 days
- Ransomware
- Used in known ransomware campaigns
- CVSS
- 4.9 MEDIUM
- EPSS (30-day exploit probability)
- 51.7% · top 1% of all CVEs
- Weakness
- CWE-22
- Attack vector
- Network, remotely reachable
Recommended actions
- 1.Apply updates per vendor instructions.
- 2.Treat as emergency change: patch or isolate internet-facing instances first.
- 3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
- 4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.
- 5.Verify offline/immutable backups and segment the affected systems. This flaw is used for ransomware initial access.
Assessment is derived automatically from the live signals above; verify against your own asset inventory.