1. Home
  2. Vulnerabilities
  3. CVE-2024-31208
6.5
MEDIUM CVSS 3.1
CVE-2024-31208
Synapse Denial of Service Vulnerability
Description

Synapse is an open-source Matrix homeserver. A remote Matrix user with malicious intent, sharing a room with Synapse instances before 1.105.1, can dispatch specially crafted events to exploit a weakness in the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.

INFO

Published Date :

April 23, 2024, 6:15 p.m.

Last Modified :

Aug. 26, 2025, 6:45 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Affected Products

The following products are affected by CVE-2024-31208 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Fedoraproject fedora
1 Matrix synapse
: Total Affected Vendor : 2 | Products : 2
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 MEDIUM [email protected]
Solution
Upgrade the matrix-synapse and rust-pythonize packages to address a denial of service vulnerability.
  • Update the matrix-synapse and/or rust-pythonize packages.
  • If necessary, ban malicious users or block malicious servers from affected rooms.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2024-31208.

URL Resource
https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a Patch
https://github.com/element-hq/synapse/releases/tag/v1.105.1 Release Notes
https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v Vendor Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET/ Mailing List Third Party Advisory
https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a Patch
https://github.com/element-hq/synapse/releases/tag/v1.105.1 Release Notes
https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v Vendor Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K/ Mailing List Third Party Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET/ Mailing List Third Party Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2024-31208 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2024-31208 weaknesses.

CAPEC-125: Flooding Flooding CAPEC-130: Excessive Allocation Excessive Allocation CAPEC-147: XML Ping of the Death XML Ping of the Death CAPEC-197: Exponential Data Expansion Exponential Data Expansion CAPEC-229: Serialized Data Parameter Blowup Serialized Data Parameter Blowup CAPEC-230: Serialized Data with Nested Payloads Serialized Data with Nested Payloads CAPEC-231: Oversized Serialized Data Payloads Oversized Serialized Data Payloads CAPEC-469: HTTP DoS HTTP DoS CAPEC-482: TCP Flood TCP Flood CAPEC-486: UDP Flood UDP Flood CAPEC-487: ICMP Flood ICMP Flood CAPEC-488: HTTP Flood HTTP Flood CAPEC-489: SSL Flood SSL Flood CAPEC-490: Amplification Amplification CAPEC-491: Quadratic Data Expansion Quadratic Data Expansion CAPEC-493: SOAP Array Blowup SOAP Array Blowup CAPEC-494: TCP Fragmentation TCP Fragmentation CAPEC-495: UDP Fragmentation UDP Fragmentation CAPEC-496: ICMP Fragmentation ICMP Fragmentation CAPEC-528: XML Flood XML Flood

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2024-31208 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2024-31208 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Aug. 26, 2025

    Action Type Old Value New Value
    Added CPE Configuration OR *cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* versions up to (excluding) 1.105.1
    Added CPE Configuration OR *cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:* *cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:* *cpe:2.3:o:fedoraproject:fedora:40:*:*:*:*:*:*:*
    Added Reference Type CVE: https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a Types: Patch
    Added Reference Type GitHub, Inc.: https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a Types: Patch
    Added Reference Type CVE: https://github.com/element-hq/synapse/releases/tag/v1.105.1 Types: Release Notes
    Added Reference Type GitHub, Inc.: https://github.com/element-hq/synapse/releases/tag/v1.105.1 Types: Release Notes
    Added Reference Type CVE: https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v Types: Vendor Advisory
    Added Reference Type GitHub, Inc.: https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v Types: Vendor Advisory
    Added Reference Type CVE: https://lists.fedoraproject.org/archives/list/[email protected]/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB/ Types: Mailing List, Third Party Advisory
    Added Reference Type GitHub, Inc.: https://lists.fedoraproject.org/archives/list/[email protected]/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB/ Types: Mailing List, Third Party Advisory
    Added Reference Type CVE: https://lists.fedoraproject.org/archives/list/[email protected]/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K/ Types: Mailing List, Third Party Advisory
    Added Reference Type GitHub, Inc.: https://lists.fedoraproject.org/archives/list/[email protected]/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K/ Types: Mailing List, Third Party Advisory
    Added Reference Type CVE: https://lists.fedoraproject.org/archives/list/[email protected]/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET/ Types: Mailing List, Third Party Advisory
    Added Reference Type GitHub, Inc.: https://lists.fedoraproject.org/archives/list/[email protected]/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET/ Types: Mailing List, Third Party Advisory
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a
    Added Reference https://github.com/element-hq/synapse/releases/tag/v1.105.1
    Added Reference https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v
    Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB/
    Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K/
    Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET/
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    May. 03, 2024

    Action Type Old Value New Value
    Added Reference GitHub, Inc. https://lists.fedoraproject.org/archives/list/[email protected]/message/RR53FNHV446CB37TP45GZ6F6HZLZCK3K/ [No types assigned]
    Added Reference GitHub, Inc. https://lists.fedoraproject.org/archives/list/[email protected]/message/R6FCCO4ODTZ3FDS7TMW76PKOSEL2TQVB/ [No types assigned]
    Added Reference GitHub, Inc. https://lists.fedoraproject.org/archives/list/[email protected]/message/VSF4NJJSTSQRJQ47PLYYSCFYKJBP7DET/ [No types assigned]
  • CVE Received by [email protected]

    Apr. 23, 2024

    Action Type Old Value New Value
    Added Description Synapse is an open-source Matrix homeserver. A remote Matrix user with malicious intent, sharing a room with Synapse instances before 1.105.1, can dispatch specially crafted events to exploit a weakness in the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.
    Added Reference GitHub, Inc. https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v [No types assigned]
    Added Reference GitHub, Inc. https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a [No types assigned]
    Added Reference GitHub, Inc. https://github.com/element-hq/synapse/releases/tag/v1.105.1 [No types assigned]
    Added CWE GitHub, Inc. CWE-770
    Added CVSS V3.1 GitHub, Inc. AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 6.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact