Security readout for executives and security teams
Plain-English summary
Synology Calendar had an XSS flaw in its Notification Center. An authenticated user could place web script or HTML in a calendar title, potentially affecting another user who views the notification. The issue is medium severity because it requires an account and user interaction, but it can still affect confidentiality, integrity, and availability.
Executive priority
Treat this as a moderate-priority patching item for Synology Calendar environments, especially shared or multi-user deployments. It is not presented as actively exploited, but it can support cross-user browser compromise within the application context.
Technical view
CVE-2018-8915 is a CWE-79 XSS vulnerability in Synology Calendar before 2.1.1-0502. The cited vector is CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L, indicating network reachability, low complexity, low privileges, required user interaction, and changed scope.
Likely exposure
Exposure is limited to Synology Calendar deployments earlier than 2.1.1-0502. Risk is higher where many authenticated users can create or edit calendar titles and where notifications are viewed by other users.
Exploitation context
The source bundle does not show KEV listing or active exploitation evidence. Exploitation requires an authenticated remote user and another user interacting with affected notification content.
Researcher notes
Evidence is limited to the CVE record and Synology advisory reference. The affected range is stated as before 2.1.1-0502, but the bundle does not provide detailed exploit mechanics, vulnerable code paths, or detection indicators.
Mitigation direction
- Upgrade Synology Calendar to 2.1.1-0502 or later.
- Review Synology advisory SA-18-06 for vendor guidance.
- Limit Calendar access to trusted authenticated users until patched.
- Review user roles that can create or edit calendar titles.
Validation and detection
- Inventory Synology Calendar deployments and record installed versions.
- Confirm affected systems are not running versions before 2.1.1-0502.
- Review who can create or edit calendar entries and titles.
- Check whether Notification Center is used by exposed user groups.
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-2018-8915 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_06CVE 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.