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Router Manager CVE-2020-27649

CRITICAL
Improper Certificate Validation (CWE-295)
2020-10-29 security@synology.com
9.0
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V12 - Secure Communication Certificate validation
Impact

CVSS score of 9.0 (CRITICAL). Attack characteristics: network attack vector, high complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the critical-severity affected system.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.
No patch listed yet 0.7% exploitation probability (EPSS)

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AnalysisAI

Improper certificate validation vulnerability in OpenVPN client in Synology Router Manager (SRM) before 1.2.4-8081 allows man-in-the-middle attackers to spoof servers and obtain sensitive information. Rated critical severity (CVSS 9.0), this vulnerability is remotely exploitable, no authentication required. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-295. Improper certificate validation vulnerability in OpenVPN client in Synology Router Manager (SRM) before 1.2.4-8081 allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate. Affected products include: Synology Router Manager. Version information: before 1.2.4.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.0 CRITICAL
AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

Improper certificate validation vulnerability in OpenVPN client in Synology Router Manager (SRM) before 1.2.4-8081 allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.

Threat Intelligence Overview

EPSS Score
0.7%
Top 51% exploitable
Exploit
POC
Public exploit code exists
Data Quality
2 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC Yes
EPSS 0.7%
Patch available No
Active threat No
Deciding rule
CRITICAL severity + public POC available
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

66
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +45
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)NVD

cpe:2.3:a:synology:router_manager:*:*:*:*:*:*:*:*
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5.6 Jan 04

Systems with microprocessors utilizing speculative execution and branch prediction may allow unauthorized disclosure of

CVE-2017-14491 CRITICAL POC
9.8 Oct 04

Heap-based buffer overflow in dnsmasq before 2.78 allows remote attackers to cause a denial of service (crash) or execut

CVE-2020-27655 CRITICAL POC
10.0 Oct 29

Improper access control vulnerability in Synology Router Manager (SRM) before 1.2.4-8081 allows remote attackers to acce

CVE-2020-27654 CRITICAL POC
9.8 Oct 29

Improper access control vulnerability in lbd in Synology Router Manager (SRM) before 1.2.4-8081 allows remote attackers

CVE-2018-1160 CRITICAL POC
9.8 Dec 20

Netatalk before 3.1.12 is vulnerable to an out of bounds write in dsi_opensess.c. Rated critical severity (CVSS 9.8), th

CVE-2020-27653 HIGH POC
8.3 Oct 29

Algorithm downgrade vulnerability in QuickConnect in Synology Router Manager (SRM) before 1.2.4-8081 allows man-in-the-m

CVE-2020-27651 HIGH POC
8.1 Oct 29

Synology Router Manager (SRM) before 1.2.4-8081 does not set the Secure flag for the session cookie in an HTTPS session,

CVE-2020-27658 MEDIUM POC
6.1 Oct 29

Synology Router Manager (SRM) before 1.2.4-8081 does not include the HTTPOnly flag in a Set-Cookie header for the sessio

CVE-2019-3870 MEDIUM POC
6.1 Apr 09

A vulnerability was found in Samba from version (including) 4.9 to versions before 4.9.6 and 4.10.2. Rated medium severi

CVE-2020-27657 MEDIUM POC
5.9 Oct 29

Cleartext transmission of sensitive information vulnerability in DDNS in Synology Router Manager (SRM) before 1.2.4-8081

CVE-2023-32956 CRITICAL
9.8 May 16

Improper neutralization of special elements used in an OS command ('OS Command Injection') vulnerability in CGI componen

CVE-2023-0077 CRITICAL
9.8 Jan 05

Integer overflow or wraparound vulnerability in CGI component in Synology Router Manager (SRM) before 1.2.5-8227-6 and 1

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