SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityAnalyzed

CVE-2021-20023

SonicWall Email Security Path Traversal Vulnerability

KEVMEDIUM 4.9EPSS 51.7%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

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.

CVSS 3.1
4.9 MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
EPSS
51.69% probability · 99th percentile
Public exploits
None in Exploit-DB
CISA KEV
Listed 3 November 2021 · due 17 November 2021 · used in ransomware campaigns
Weakness
CWE-22
Affected
sonicwall/email security · sonicwall/email security appliance 9000 firmware · sonicwall/email security appliance 3300 firmware · sonicwall/email security appliance 4300 firmware · sonicwall/email security appliance 8300 firmware · sonicwall/email security appliance 5000 firmware · sonicwall/email security appliance 7000 firmware · sonicwall/email security appliance 5050 firmware · sonicwall/email security appliance 7050 firmware · sonicwall/email security virtual appliance · sonicwall/hosted email security
Source
PSIRT@sonicwall.com
EPSS trend
0%28%55%30 October 2026: 51.69%30 October 202630 October 2026

EPSS 51.7% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

CISA notes

Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-20023

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.