Threats / SonicWall / CVE-2021-20022
CVE-2021-20022
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
SonicWall Email Security vulnerability
SonicWall Email Security allows post-authenticated attackers to upload dangerous file types, enabling privilege escalation when chained with other vulnerabilities in active exploitation.
Verdict
Today item, not a backlog item.
An authenticated attacker can upload malicious files to SonicWall Email Security systems. This vulnerability is actively exploited in the wild as part of multi-stage attack chains leading to privilege escalation and ransomware deployment.
CISA KEV Yes · 2021-11-035Ransomware use Flagged5EPSS 0.16509 (verify live)6CVSS 7.2 (CISA)4CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
7 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.16509 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.2 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H) · Affected: SonicWall, SonicWall Email Security. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-434 Unrestricted File Upload — weakness family: Path traversal / file.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 208 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I authenticate to the Email Security appliance using valid credentials or a compromised account.
Business
Legitimate user accounts or service credentials are exposed or compromised, creating an entry point.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I upload a malicious file bypassing type restrictions to establish persistence or execute code.
Business
Attackers gain ability to place executable or script content on trusted infrastructure.
3
Lateral reach — past segmentation narrative 3
Attacker
I chain this upload with CVE-2021-20021 and CVE-2021-20023 to escalate privileges on the system.
Business
Attackers achieve administrative control of the email security gateway, a critical network chokepoint.
4
Data at risk — exfiltration narrative 4
Attacker
I deploy ransomware or lateral movement tools across the network from the compromised appliance.
Business
Organization experiences widespread encryption of data, email disruption, and operational shutdown.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05