CVE-2021-20023
Published: November 3, 2021
Official 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.
CISA KEV Advisory
SonicWall Email Security Path Traversal 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.
Apply updates per vendor instructions.
Risk Analysis
This path traversal vulnerability in SonicWall Email Security allows a post-authenticated attacker to read arbitrary files on the remote host. It is part of a known exploit chain that, when combined with other vulnerabilities, can lead to privilege escalation. The high EPSS score of 0.48573 and its presence in CISA's KEV highlight the urgency of addressing this actively exploited flaw.
This vulnerability is actively exploited in the wild as part of a larger exploit chain and is listed in CISA's Known Exploited Vulnerabilities catalog. Exploitation requires prior authentication.
Apply all available security updates for SonicWall Email Security to patch this path traversal vulnerability and associated flaws. Implement strong authentication and monitor for suspicious file access attempts.
Technical Analysis
CVE-2021-20023 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2021-20023 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Exploit & PoC Resources
All References (1)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-20023 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1