Security readout for executives and security teams
Plain-English summary
This is a critical SQL injection flaw in end-of-life SonicWall Secure Remote Access/SMA100 appliances. An unauthenticated attacker could potentially compromise confidentiality, integrity, and availability. Because CISA lists it in KEV, organizations should treat exposed affected devices as urgent risk.
Executive priority
Treat this as a high-priority remediation item for any exposed affected SonicWall remote-access appliance. KEV listing and critical CVSS create board-relevant risk, especially because remote-access infrastructure often protects privileged paths into the business.
Technical view
CVE-2021-20028 is CWE-89 SQL injection affecting SonicWall SRA/SMA100 appliances running all 8.x firmware and 9.0.0.9-26sv or earlier. The CVSS 3.1 score is 9.8: network reachable, low complexity, no privileges, no user interaction, with high confidentiality, integrity, and availability impact.
Likely exposure
Most likely exposure is an internet-facing SonicWall SRA/SMA100 remote access appliance on affected firmware. Internal-only devices still matter, but public VPN or remote-access placement increases urgency. Evidence does not identify affected cloud services or unrelated SonicWall product lines.
Exploitation context
CISA KEV status indicates known exploitation. The provided sources do not state exploit volume, attacker identity, exploited paths, or whether exploitation is ongoing today. Do not infer compromise solely from product presence; validate firmware, exposure, and logs.
Researcher notes
Evidence supports critical severity, SQL injection classification, affected firmware ranges, and KEV exploitation status. The bundle does not provide exploit mechanics, indicators, patch identifiers, or forensic artifacts. Research should stay focused on asset identification, exposure confirmation, vendor guidance, and defensive telemetry.
Mitigation direction
- Inventory SonicWall SRA/SMA100 appliances and record exact firmware versions.
- Prioritize affected internet-facing appliances for immediate remediation planning.
- Consult SonicWall PSIRT guidance before selecting update, migration, or replacement actions.
- Retire or replace end-of-life affected SRA appliances where vendor guidance requires it.
- Reduce external exposure for affected appliances until vendor-directed remediation is complete.
- Increase monitoring for unusual authentication, database, and remote-access appliance activity.
Validation and detection
- Confirm whether any appliance runs 8.x firmware or 9.0.0.9-26sv or earlier.
- Check whether the management or remote-access interface is internet reachable.
- Review SonicWall PSIRT advisory for affected status and remediation direction.
- Search appliance logs for suspicious access around remote-access and database-backed functions.
- Verify remediation by confirming firmware or replacement state against vendor guidance.
Public sources used
Michael Williams reviewed this cited source version on .
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-89: Database access and collection lookup
Injection into data stores can inform collection, data access, and exfiltration detection reviews. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupDatabase behavior lookup
The CVE wording references database injection or access, so collection and exfiltration review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-20028 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0017CVE reference · x_refsource_CONFIRM
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-20028CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.