VDB-244097 · CVE-2023-43796 · Nessus 234734

Matrix Synapse prior 1.95.1/1.96.0rc1 information disclosure

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.
5.2	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Matrix Synapse. It has been rated as problematic. The impacted element is an unknown function. The manipulation leads to information disclosure. This vulnerability is uniquely identified as CVE-2023-43796. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Matrix Synapse. It has been rated as problematic. This issue affects an unknown function. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. The summary by CVE is:

Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

The weakness was disclosed 10/31/2023. The advisory is shared at github.com. The identification of this vulnerability is CVE-2023-43796 since 09/22/2023. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1592 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 234734 (Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS : Synapse vulnerabilities (USN-7444-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.95.1 or 1.96.0rc1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (234734). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

Matrix

Name

Synapse

License

open-source

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

CNA Base Score: 5.3
CNA Vector (GitHub, Inc.): 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

Exploitinginfo

Class: Information disclosure
CWE: CWE-200 / CWE-284 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 234734
Nessus Name: Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS : Synapse vulnerabilities (USN-7444-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Synapse 1.95.1/1.96.0rc1
Patch: github.com

Timelineinfo

09/22/2023 🔍
10/31/2023 +39 days 🔍
10/31/2023 +0 days 🔍
04/23/2025 +540 days 🔍

Sourcesinfo

Advisory: daec55e1fe120c564240c5386e77941372bf458f
Status: Confirmed

CVE: CVE-2023-43796 (🔍)
GCVE (CVE): GCVE-0-2023-43796
GCVE (VulDB): GCVE-100-244097

Entryinfo

Created: 10/31/2023 18:09
Updated: 04/23/2025 15:02
Changes: 10/31/2023 18:09 (47), 11/24/2023 17:47 (2), 11/24/2023 17:55 (2), 04/23/2025 15:02 (17)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.