Security readout for executives and security teams
Plain-English summary
Synology Antivirus Essential had a critical flaw in its quarantine feature. A remote authenticated user could gain elevated privileges through unspecified vectors. The issue affects versions before 1.4.8-2801, so business risk is concentrated on Synology systems still running older package versions.
Executive priority
Treat as high-priority remediation for Synology environments because successful exploitation could affect confidentiality, integrity, and availability. Urgency is highest where many users can authenticate or devices are remotely accessible.
Technical view
CVE-2021-27648 is a CWE-610 externally controlled reference issue in Synology Antivirus Essential quarantine functionality. The CVSS 3.1 score is 9.0, with network access, low privileges, user interaction required, and changed scope. Public details do not specify the exact attack vector.
Likely exposure
Organizations using Synology NAS devices with Antivirus Essential installed before version 1.4.8-2801 are the likely exposed population. Exposure requires an authenticated remote user, not anonymous internet access based on the CVE description.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Exploit mechanics are not publicly described in the supplied bundle, and the vendor reference gives the authoritative remediation context.
Researcher notes
The source bundle identifies CWE-610 and quarantine functionality, but vectors remain unspecified. Validation should focus on version exposure and access context, not exploit reproduction. Avoid assuming anonymous exploitation or confirmed exploitation without new evidence.
Mitigation direction
- Upgrade Synology Antivirus Essential to 1.4.8-2801 or later.
- Review Synology advisory Synology_SA_21_15 for current vendor guidance.
- Limit Synology package and administration access to trusted authenticated users.
- Prioritize remediation on internet-reachable or shared-user NAS deployments.
Validation and detection
- Inventory Synology NAS devices running Antivirus Essential.
- Check installed package versions against 1.4.8-2801.
- Confirm affected systems received the vendor package update.
- Review account access for low-privileged users on exposed devices.
- Monitor vendor advisory updates for additional affected-version details.
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-610: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupCVE-2021-27648 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 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/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:R/S:C/C:H/I:H/A:H2.36Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9CriticalVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/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_15CVE 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.
Externally Controlled Reference to a Resource in Another Sphere
Externally Controlled Reference to a Resource in Another Sphere represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.