Security readout for executives and security teams
Plain-English summary
CVE-2018-13296 is a denial-of-service issue in Synology MailPlus Server TLS handling. A remote attacker could consume server resources by initiating TLS renegotiation, potentially disrupting mail service availability. The issue affects versions before 2.0.5-0606.
Executive priority
Treat this as a high-priority availability risk for organizations relying on Synology MailPlus Server for email. It does not indicate data theft or privilege escalation, but service disruption can still create business impact.
Technical view
Synology MailPlus Server before 2.0.5-0606 allowed uncontrolled resource consumption in its TLS configuration through client-initiated renegotiation. The CVSS 3.0 vector is network-reachable, low complexity, no privileges, no user interaction, with high availability impact only.
Likely exposure
Exposure is most likely where Synology MailPlus Server older than 2.0.5-0606 accepts TLS connections from untrusted networks or the internet. The source bundle does not identify affected platforms beyond Synology MailPlus Server.
Exploitation context
The sources describe remote denial-of-service potential through client-initiated TLS renegotiation. CISA KEV status is false in the bundle, and no cited source here reports active exploitation or public exploit use.
Researcher notes
Evidence is limited to the CVE description and Synology advisory reference. The key condition is TLS client-initiated renegotiation causing resource exhaustion in MailPlus Server before 2.0.5-0606. Do not infer broader Synology product exposure from this bundle.
Mitigation direction
- Upgrade Synology MailPlus Server to 2.0.5-0606 or later.
- Review Synology advisory SA-18-43 for vendor-specific guidance.
- Restrict public TLS access to MailPlus Server where business permits.
- Monitor service capacity and availability during remediation.
Validation and detection
- Inventory all Synology MailPlus Server instances and versions.
- Confirm no exposed instance is older than 2.0.5-0606.
- Identify internet-facing TLS endpoints for MailPlus Server.
- Review availability monitoring for unexplained MailPlus Server resource exhaustion.
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
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Open ATT&CK lookupCVE-2018-13296 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.5HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.synology.com/security/advisory/Synology_SA_18_43CVE 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.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.