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Weekly Signal
Live intelligence Updated 21 Aug 2026 · 22:11 UTC

SonicWall · Email Security, Email Security Appliance 3300 Firmware, Email Security Appliance 4300 Firmware +9 more

CVE-2021-20023

SonicWall Email Security Path Traversal Vulnerability

Recommended action

Validate affected assets and exposure now, then remediate on an accelerated schedule. SonicWall Security advisory SNWLID 2021 0010

View response plan
CVSS4.9
EPSS50.2%
KEVYes
ExploitationConfirmed exploitation
RemediationNot yet verified ↓

Assessment

Why it matters

CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 50.2%; technical severity is CVSS 4.9.

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.

Who should care

  • Teams operating Email Security, Email Security Appliance 3300 Firmware, Email Security Appliance 4300 Firmware +9 more
  • Vulnerability and exposure management teams
  • Security operations teams monitoring exploitation activity

Response plan

What I would do

  1. Confirm whether Email Security, Email Security Appliance 3300 Firmware, Email Security Appliance 4300 Firmware +9 more is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. SonicWall Security advisory SNWLID 2021 0010
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Treatment intelligence

Remediation intelligence

Not yet verified

Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.

Verification noteAutomated link verification has not completed for this guidance yet.

Advisory

Required Action

Technical details

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
CWE
CWE-22
Affected versions
SonicWall Email Security (End Excluding 10.0.9.6173); SonicWall Email Security Appliance 3300 Firmware (End Excluding 10.0.9.6177); SonicWall Email Security Appliance 4300 Firmware (End Excluding 10.0.9.6177); SonicWall Email Security Appliance 5000 Firmware (End Excluding 10.0.9.6177); SonicWall Email Security Appliance 5050 Firmware (End Excluding 10.0.9.6177); SonicWall Email Security Appliance 7000 Firmware (End Excluding 10.0.9.6177); SonicWall Email Security Appliance 7050 Firmware (End Excluding 10.0.9.6177); SonicWall Email Security Appliance 8300 Firmware (End Excluding 10.0.9.6177)
Fixed versions
SonicWall Email Security (Fixed from 10.0.9.6173); SonicWall Email Security Appliance 3300 Firmware (Fixed from 10.0.9.6177); SonicWall Email Security Appliance 4300 Firmware (Fixed from 10.0.9.6177); SonicWall Email Security Appliance 5000 Firmware (Fixed from 10.0.9.6177); SonicWall Email Security Appliance 5050 Firmware (Fixed from 10.0.9.6177); SonicWall Email Security Appliance 7000 Firmware (Fixed from 10.0.9.6177); SonicWall Email Security Appliance 7050 Firmware (Fixed from 10.0.9.6177); SonicWall Email Security Appliance 8300 Firmware (Fixed from 10.0.9.6177)
Published
20 April 2021
Attack vector
Network
Privileges required
High
User interaction
None

Signal timeline

  1. CVE published
  2. Added to CISA KEV
  3. Latest EPSS score: 50.2%
  4. Signal calculated at 77

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.