Security readout for executives and security teams
Plain-English summary
Synology Mail Station had a critical command injection flaw. A logged-in remote user could potentially make the mail component run operating-system commands. For an affected mail server, this could lead to full compromise of confidentiality, integrity, and availability.
Executive priority
Treat as urgent for any affected Synology mail deployment. The issue is critical, remotely reachable after authentication, and could allow command execution on the underlying system.
Technical view
CVE-2021-43928 is CWE-78 OS command injection in Synology Mail Station’s mail sending and receiving component before 20211105-10315. The CVSS 3.1 score is 9.9, with network attack vector, low complexity, low privileges, no user interaction, scope change, and high CIA impact.
Likely exposure
Exposure is limited to organizations running Synology Mail Station before 20211105-10315. The attacker must be authenticated, but access is remote and no user interaction is required, making shared or internet-reachable Mail Station deployments higher priority.
Exploitation context
The provided sources do not identify active exploitation, public exploit use, or CISA KEV listing. Vectors are unspecified, so defenders should avoid assuming only one interface or workflow is affected.
Researcher notes
The advisory and CVE record do not describe the exact vulnerable vector. Validation should focus on version confirmation, access paths, account exposure, and log review rather than exploit reproduction.
Mitigation direction
- Update Synology Mail Station to 20211105-10315 or later.
- Review Synology advisory Synology_SA_21_28 for vendor-specific guidance.
- Limit Mail Station access to trusted authenticated users until patched.
- Audit accounts with Mail Station access and remove unnecessary access.
Validation and detection
- Inventory Synology systems running Mail Station.
- Confirm installed Mail Station version is 20211105-10315 or later.
- Check whether remote authenticated users can access Mail Station.
- Review Synology logs for suspicious authenticated activity around mail operations.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-78: Command execution behavior lookup
Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-43928 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
- 9.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/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.
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:L/UI:N/S:C/C:H/I:H/A:H3.16Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.9CriticalVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.synology.com/security/advisory/Synology_SA_21_28CVE reference · x_refsource_CONFIRM
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.