Security readout for executives and security teams
Plain-English summary
Synology Drive versions before 1.0.2-10275 had an authenticated XSS flaw in file-sharing notification toasts. A malicious filename could cause script or HTML to run when another user interacted with the affected notification, risking limited data exposure, session misuse, or UI manipulation.
Executive priority
Treat as a routine but real remediation item. It is not marked actively exploited, but authenticated XSS can affect user trust and session security in shared file environments.
Technical view
CVE-2018-8921 is CWE-79 in Synology Drive File Sharing Notify Toast. The CVSS 3.0 vector is AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L, meaning network-accessible, low complexity, authenticated attacker, user interaction required, and changed scope with low CIA impact.
Likely exposure
Exposure is limited to organizations running Synology Drive before 1.0.2-10275 with authenticated users able to create or share files that trigger notification toasts for other users.
Exploitation context
The source bundle does not show CISA KEV listing or other evidence of active exploitation. Exploitation requires an authenticated remote user and victim interaction with the affected notification path.
Researcher notes
Evidence supports Synology Drive before 1.0.2-10275 only. The bundle identifies the vulnerable UI component and filename vector, but does not provide exploit details, broad product scope, or additional mitigations beyond vendor guidance.
Mitigation direction
- Upgrade Synology Drive to 1.0.2-10275 or later.
- Check Synology advisory for any environment-specific guidance.
- Restrict Synology Drive access to trusted users until upgraded.
- Review user accounts with file-sharing permissions.
Validation and detection
- Inventory Synology Drive versions across all NAS devices.
- Confirm affected systems are at 1.0.2-10275 or later.
- Verify Drive access is limited to expected authenticated users.
- Review logs for suspicious file names or sharing activity.
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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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-2018-8921 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
- 6.5 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
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:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L2.33.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
6.5MediumVector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://www.synology.com/en-global/support/security/Synology_SA_18_11CVE 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 Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.