Security readout for executives and security teams
Plain-English summary
Synology Docker before 18.09.0-0515 had a path traversal flaw in container volume management. An already highly privileged local user could read or write files outside intended directories. This is not described as remote unauthenticated compromise, but it can undermine confidentiality and integrity on affected Synology systems.
Executive priority
Prioritize remediation on Synology systems used for sensitive file storage, backups, or shared administration. The issue is high severity but locally gated, so urgency depends on who has privileged local access and how critical the NAS data is.
Technical view
CVE-2021-33183 is CWE-22 path traversal in Synology Docker container volume management. The CVSS 3.1 score is 7.9 with local access, low complexity, high privileges, no user interaction, changed scope, high confidentiality impact, high integrity impact, and no availability impact.
Likely exposure
Organizations are exposed if they run Synology Docker versions before 18.09.0-0515 on Synology systems, especially where multiple local administrators or high-privilege users can manage containers or volumes.
Exploitation context
The supplied sources do not report active exploitation, and the CVE is not marked KEV. Exploitation requires local access and high privileges, which limits broad internet-scale risk but keeps insider, compromised-admin, and shared-appliance scenarios material.
Researcher notes
Public details are sparse: the vector is unspecified beyond container volume management path traversal. Avoid assuming a specific exploit path. Validation should focus on version exposure, privilege boundaries, volume configuration review, and vendor advisory confirmation.
Mitigation direction
- Upgrade Synology Docker to 18.09.0-0515 or later where available.
- Review the Synology advisory for product-specific fixed releases and guidance.
- Limit Docker management access to trusted administrators only.
- Review local high-privilege accounts on affected Synology systems.
- Monitor for unexpected file changes outside expected container volume paths.
Validation and detection
- Inventory Synology systems running the Docker package.
- Confirm Docker package versions are not earlier than 18.09.0-0515.
- Identify users or groups with Docker or administrator privileges.
- Review container volume configurations for unusual host path exposure.
- Check file integrity and logs for unexpected changes by privileged local users.
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-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection 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 lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupContainer behavior lookup
The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-33183 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
- High
- CVSS
- 7.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
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:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N1.55.8Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.9HighVector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.synology.com/security/advisory/Synology_SA_21_08CVE 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.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.