CVE-2025-30355
Synapse Denial of Federation Vulnerability
Description
Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1. No known workarounds are available.
INFO
Published Date :
March 27, 2025, 1:15 a.m.
Last Modified :
Aug. 26, 2025, 7:24 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
---|---|---|---|---|---|---|
CVSS 3.1 | HIGH | [email protected] | ||||
CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Synapse to version 1.127.1 or later.
- Verify federation capabilities after updating.
Public PoC/Exploit Available at Github
CVE-2025-30355 has a 1 public
PoC/Exploit
available at Github.
Go to the Public Exploits
tab to see the list.
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-2025-30355
.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-30355
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-2025-30355
weaknesses.
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).
None
HTML Python Shell
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-30355
vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-30355
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 CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE NVD-CWE-noinfo Added CPE Configuration OR *cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* versions up to (excluding) 1.127.1 Added Reference Type GitHub, Inc.: https://github.com/element-hq/synapse/commit/2277df2a1eb685f85040ef98fa21d41aa4cdd389 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/element-hq/synapse/releases/tag/v1.127.1 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/element-hq/synapse/security/advisories/GHSA-v56r-hwv5-mxg6 Types: Vendor Advisory -
New CVE Received by [email protected]
Mar. 27, 2025
Action Type Old Value New Value Added Description Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1. No known workarounds are available. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H Added CWE CWE-20 Added Reference https://github.com/element-hq/synapse/commit/2277df2a1eb685f85040ef98fa21d41aa4cdd389 Added Reference https://github.com/element-hq/synapse/releases/tag/v1.127.1 Added Reference https://github.com/element-hq/synapse/security/advisories/GHSA-v56r-hwv5-mxg6