CVE-2018-8927
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper authorization vulnerability in SYNO.Cal.Event in Calendar before 2.1.2-0511 allows remote authenticated users to create arbitrary events via the (1) cal_id or (2) original_cal_id parameter.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThis is an insecure direct object reference (IDOR) vulnerability in Synology Calendar where the application fails to properly authorize event creation requests. An authenticated user can manipulate the cal_id or original_cal_id parameters to create events in calendars they do not own or have permissions for, bypassing intended access controls.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 2.1.2-0511CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Check Synology Calendar versionAccess Synology Package Center and locate Synology Calendar in the installed package list to view the current version numberAffected if The installed version is lower than 2.1.2-0511 (e.g., 2.1.1 or earlier)
-
Verify calendar sharing is enabledAccess Synology Calendar via the web interface, navigate to Calendar settings, and check if sharing permissions are configured for any calendarsAffected if Calendar sharing or shared calendar access is enabled and the installed version is vulnerable
-
Review event audit logs for unauthorized creationAccess Synology Calendar logs through the DSM Log Center or check calendar event history for entries where the creating user does not own the target calendarAffected if Event creation logs show activity from users creating events in calendars they do not own or are not explicitly shared with
-
Inspect API request parametersIf you have access to web server logs or proxy traffic, examine POST requests to the calendar application endpoint for unexpected cal_id or original_cal_id valuesAffected if API requests contain cal_id values that do not correspond to the authenticated user's owned calendars
A user is affected if they are running Synology Calendar version lower than 2.1.2-0511 and have calendar sharing or shared calendar access enabled in their environment.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data2.1.2-0511
Upgrade Synology Calendar to version 2.1.2-0511 or later, which contains the proper authorization checks. If immediate upgrade is not possible, restrict calendar sharing permissions and monitor for unauthorized event creation.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-8927 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2018-8927 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data