Synology CardDAV Server up to 6.0.7 /principals credentials management

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.

A vulnerability was found in Synology CardDAV Server up to 6.0.7 and classified as critical. Affected by this issue is an unknown code block of the file /principals. The manipulation with an unknown input leads to a credentials management vulnerability. Using CWE to declare the problem leads to CWE-255. Impacted is confidentiality, integrity, and availability. CVE summarizes:

An improper restriction of excessive authentication attempts vulnerability in /principals in Synology CardDAV Server before 6.0.7-0085 allows remote attackers to obtain user credentials via a brute-force attack.

The bug was discovered 11/06/2017. The weakness was shared 11/07/2017 (Website). The advisory is shared for download at This vulnerability is handled as CVE-2017-15887 since 10/25/2017. The attack may be launched remotely. The requirement for exploitation is a simple authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1552.

The vulnerability was handled as a non-public zero-day exploit for at least 1 days. During that time the estimated underground price was around $0-$5k.

Upgrading to version 6.0.7-0085 eliminates this vulnerability.






CPE 2.3info

CPE 2.2info


VulDB CVSS-B Score: 🔍
VulDB CVSS-BT Score: 🔍
VulDB Vector: 🔍
VulDB Reliability: 🔍


VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.9

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔍



VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍


Class: Credentials management
CWE: CWE-255
ATT&CK: T1552

Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍


Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍


Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: CardDAV Server 6.0.7-0085


10/25/2017 🔍
11/06/2017 +12 days 🔍
11/07/2017 +1 days 🔍
11/07/2017 +0 days 🔍
11/08/2017 +1 days 🔍
01/06/2023 +1885 days 🔍



Advisory: SA_17_64
Status: Not defined
Confirmation: 🔍

CVE: CVE-2017-15887 (🔍)


Created: 11/08/2017 07:45 AM
Updated: 01/06/2023 02:55 PM
Changes: 11/08/2017 07:45 AM (59), 12/04/2019 08:15 PM (2), 01/06/2023 02:55 PM (4)
Complete: 🔍


No comments yet. Languages: en.

Please log in to comment.

Do you need the next level of professionalism?

Upgrade your account now!