CVE-2021-20021
Sonicwall Email Security ≤ 10.0.9.6103
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2021-20021 is a critical-severity Improper Privilege Management (CWE-269) vulnerability in Sonicwall Email Security. Its CVSS base score is 9.8 (Critical).
Operationally, ranked in the top 0.2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A vulnerability tracked as CVE-2021-20021 exists in SonicWall Email Security version 10.0.9.x and is associated with CWE-269. It permits an unauthenticated remote attacker to create an administrative account by submitting a specially crafted HTTP request to the affected system. The flaw carries a CVSS 3.1 base score of 9.8, reflecting network attack vector, low complexity, and no required privileges or user interaction, with high impact on confidentiality, integrity, and availability.
An attacker with network access to the SonicWall Email Security appliance can exploit the issue to provision a new administrative account. Successful exploitation grants the attacker full administrative control over the email security platform, enabling further actions such as altering configuration, accessing sensitive data, or deploying additional malicious components.
SonicWall has published advisory SNWLID-2021-0007 detailing the issue, and the vulnerability appears in CISA's catalog of known exploited vulnerabilities, confirming observed in-the-wild exploitation. Organizations should apply vendor patches or mitigations referenced in the advisory to address the exposure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-7484
Vulnerability Data
A vulnerability in the SonicWall Email Security version 10.0.9.x allows an attacker to create an administrative account by sending a crafted HTTP request to the remote host.
- CWE(s)
- KEV Date Added
- 03 November 2021
Related Threats
Threat-Actor AttributionAI
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Policy addresses roles, responsibilities, and privilege management to prevent improper privilege assignments.
Access supervision ensures privileges are assigned and managed without improper escalation or retention.
Assigning group/role memberships and access authorizations (privileges) while reviewing accounts addresses improper privilege management.
Enforces proper privilege management by requiring all decisions through the verified reference monitor.
By mandating division of duties across roles, the control enforces proper privilege management and prevents a single entity from controlling an entire sensitive process.
Implements core proper privilege management by restricting to only required rights.
Policy requires training on privilege management and least privilege, making it harder to exploit improper privilege management weaknesses.
Training covers proper privilege management practices, making incorrect privilege assignments less likely.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
A.5.15 directly mandates determining access requirements, defining/enforcing topic-specific access control policy, assigning rights/restrictions by entity/role, consistency with classification, need-to-know, privileged access restrictions, segregation, formal authorization, and dynamic rules — which stops most improper privilege management from being exploitable; bounded remainder is flawed implementation of those rules (e.g. incorrect mapping or enforcement bugs).
A.5.18 directly governs the provisioning, review, modification and timely revocation of access rights (including for role changes, termination and privilege levels), which stops most improper privilege spheres from being exploitable even if the assignment flaw exists; the bounded remainder is flaws in the underlying enforcement mechanism itself (e.g. AC-3/A.8.3)
Defining and communicating authorization levels for each role limits the assignment of excessive or unnecessary privileges.
Logging every use of privileges and protecting those records makes it harder for an attacker who has obtained elevated rights to operate without leaving evidence.
A.8.2 directly controls the identification, allocation, review, expiry, temporary use, and separation of privileged rights per policy, which prevents most improper privilege management (CWE-269) by design; the bounded remainder is flawed tracking/checking logic inside the product's own enforcement code (the AC-3 slice of 269).
A.8.27 mandates security-by-design principles including least privilege, default deny, fail securely, defence in depth, security architecture integration, hardening, and zero-trust verification of every request; these directly stop most improper privilege spheres from being exploitable even if the assignment flaw remains, with a bounded remainder (e.g. certain legacy or safety-overridden controls).
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.