Security readout for executives and security teams
Plain-English summary
CVE-2021-29086 is a Synology DSM web API issue that could let a remote, unauthenticated attacker obtain sensitive information. The public details do not specify exactly what information is exposed or the request path involved. Business urgency is moderate: prioritize internet-facing DSM systems and confirm they are updated beyond the affected version range.
Executive priority
Treat as a moderate-priority remediation item, elevated for internet-facing NAS infrastructure. The known impact is information exposure rather than system takeover, but unauthenticated network reachability makes exposed DSM systems worth addressing promptly.
Technical view
The vulnerability is CWE-200 in the webapi component of Synology DiskStation Manager before 6.2.3-25426-3. CVSS 3.1 is 5.3 with network access, low complexity, no privileges, and no user interaction. Impact is limited to confidentiality; integrity and availability are not listed as affected.
Likely exposure
Exposure is most relevant where DSM management or web API services are reachable from untrusted networks. The source bundle only identifies DSM before 6.2.3-25426-3 and does not enumerate models, configurations, or specific vulnerable endpoints.
Exploitation context
No provided source confirms active exploitation, and the CVE is not marked in KEV. The attack vector is remote and unauthenticated, but public details describe only unspecified vectors, so practical exploitability cannot be validated from the bundle alone.
Researcher notes
The public description omits affected endpoints, information classes, and vectors. Validation should focus on version and exposure checks rather than exploit reproduction. Do not assume broader Synology products are affected without vendor confirmation.
Mitigation direction
- Upgrade Synology DSM to 6.2.3-25426-3 or a later vendor-supported release.
- Review Synology advisory SA-20-26 for product-specific update guidance.
- Restrict DSM management access to trusted networks while remediation is pending.
- Reduce unnecessary internet exposure for DSM web API services.
Validation and detection
- Inventory Synology DSM systems and record installed DSM versions.
- Flag DSM versions earlier than 6.2.3-25426-3 for remediation.
- Confirm whether DSM management interfaces are internet-accessible.
- Review logs for unusual remote access to DSM web services.
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-200: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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-2021-29086 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
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.synology.com/security/advisory/Synology_SA_20_26CVE 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.
Exposure of Sensitive Information to an Unauthorized Actor
Exposure of Sensitive Information to an Unauthorized Actor represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.