Security readout for executives and security teams
Plain-English summary
Synology Calendar before 2.3.1-0617 contains a command injection flaw. A remote, unauthenticated attacker could use a crafted X-Real-IP header to run commands on the affected system. This matters most for internet-facing Synology Calendar deployments.
Executive priority
Treat this as a high-priority remediation for exposed Synology Calendar systems because it is unauthenticated, network-reachable command injection. Prioritize inventory, version verification, and upgrade rather than broad emergency response unless local evidence shows exploitation.
Technical view
CVE-2019-11829 is CWE-78 OS command injection in drivers_syno_import_user.php in Synology Calendar before 2.3.1-0617. The CVSS 3.1 score is 7.3, with network attack vector, low complexity, no privileges, and no user interaction required.
Likely exposure
Exposure is likely where Synology Calendar is installed below 2.3.1-0617, especially if reachable from the internet or through a reverse proxy. The provided sources do not enumerate affected DSM versions, device models, or CPEs.
Exploitation context
The source bundle says arbitrary command execution is possible through a crafted X-Real-IP header. It does not cite active exploitation, public exploit use, or inclusion in CISA KEV; KEV is marked false.
Researcher notes
Evidence identifies the vulnerable component and attacker-controlled header, but not exploit telemetry, patch internals, or affected device matrix. Validation should stay focused on product version, exposure path, and logs rather than assuming broader Synology product impact.
Mitigation direction
- Upgrade Synology Calendar to 2.3.1-0617 or later per Synology guidance.
- Restrict external access to Synology Calendar until version status is confirmed.
- Review reverse proxy handling of client IP headers.
- Check Synology advisory for any environment-specific remediation notes.
Validation and detection
- Inventory Synology NAS systems running Calendar.
- Verify installed Calendar version against 2.3.1-0617.
- Confirm whether Calendar is internet-facing or proxy-exposed.
- Review logs for suspicious Calendar requests involving X-Real-IP headers.
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-78: Command execution behavior lookup
Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2019-11829 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
- High
- CVSS
- 7.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L3.93.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://www.synology.com/security/advisory/Synology_SA_19_12CVE 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 Special Elements used in an OS Command ('OS Command Injection')
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.