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CalendarApplication · Synology

CVE-2019-11829

CRITICAL · 9.8 CVSS v3.1 Published 2019-06-30
Fix available
A fix is available. Upgrade to 2.3.1-0617 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
OS command injection vulnerability in drivers_syno_import_user.php in Synology Calendar before 2.3.1-0617 allows remote attackers to execute arbitrary commands via the crafted 'X-Real-IP' header.

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 confidence

OS command injection vulnerability in Synology Calendar's drivers_syno_import_user.php allows remote attackers to execute arbitrary commands via a crafted X-Real-IP HTTP header. The vulnerability stems from improper sanitization of the HTTP header value before passing it to a system call.

MitigationUpgrade Synology Calendar to version 2.3.1-0617 or later. If immediate patching is not feasible, restrict network access to the Calendar application or disable it until the update can be applied.

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
CalendarApplication
Affected:< 2.3.1-0617

CVSS 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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Synology Calendar is installed
    Log into Synology DSM, open Package Center, and look for Synology Calendar in the installed package list. Alternatively, check via SSH with: cat /var/packages/SynologyCalendar/conf/VERSION 2>/dev/null
    Affected if Synology Calendar package is not found in Package Center
  2. Check installed Synology Calendar version
    In Package Center, click on Synology Calendar and view the version number. Or via SSH: cat /var/packages/SynologyCalendar/conf/VERSION 2>/dev/null | grep -E '^(major|minor|build)='
    Affected if The installed version is lower than 2.3.1-0617 (e.g., 2.3.0-0501, 2.2.x, etc.)
  3. Locate the vulnerable script
    Via SSH or File Station, navigate to the web directory (typically /var/packages/SynologyCalendar/target/webapi or /usr/syno/synologycalendar/target/webapi) and verify the presence of drivers_syno_import_user.php
    Affected if The file drivers_syno_import_user.php exists in the webapi directory
  4. Determine Calendar application accessibility
    Check if Synology Calendar web interface is accessible from network. In DSM, go to Control Panel > Application Portal > Reverse Proxy or directly attempt to access the Calendar URL (typically https://[nas-ip]/calendar/)
    Affected if The Calendar application is reachable from network without restriction

If Synology Calendar is installed with a version below 2.3.1-0617 and the vulnerable script drivers_syno_import_user.php is accessible, the environment is affected by CVE-2019-11829.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 2.3.1-0617 or later
Fixed in 2.3.1-0617
Interim mitigation

Upgrade Synology Calendar to version 2.3.1-0617 or later. If immediate patching is not feasible, restrict network access to the Calendar application or disable it until the update can be applied.

Recommended fix High confidence

Synology Calendar 2.3.1-0617 or later

  1. 1. Log in to your Synology NAS and open Package Center
  2. 2. Locate Synology Calendar in the installed packages list
  3. 3. Check the current version to confirm it is below 2.3.1-0617
  4. 4. Update Synology Calendar to version 2.3.1-0617 or later through Package Center
  5. 5. Verify the update was successful by confirming the installed version is 2.3.1-0617 or higher

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Calendar Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-11829 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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