CVE-2018-16515: Matrix Synapse Improper Signature Validation
Summary
CVE-2018-16515: Matrix Synapse Improper Signature Validation. Affects matrix-synapse across 2 version ranges.
< 0.33.2.1
>= 0.33.3, < 0.33.3.1
Fixed in 0.33.2.1 or 0.33.3.1, depending on the release line you run. How to fix ↓
Also tracked for
- matrix-synapse · Debian:13
The same CVE-2018-16515 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
Matrix Synapse is an open-source messaging server that enables secure communication and collaboration. It provides a decentralized and federated communication infrastructure for instant messaging and VoIP. The vulnerability in question, identified as CVE-2018-16515, affects Matrix Synapse versions prior to 0.33.3.1. This vulnerability arises from improper transaction and event signature validation, allowing remote attackers to spoof events and potentially exploit other unspecified impacts.
Vulnerability Detail
The vulnerability in Matrix Synapse before version 0.33.3.1 stems from the inadequate validation of transaction and event signatures. This flaw enables remote attackers to manipulate events and potentially cause various detrimental effects. By exploiting this vulnerability, attackers can impersonate legitimate users, modify or delete messages, and potentially gain unauthorized access to sensitive information. The impact of this vulnerability can be severe, compromising the integrity and confidentiality of the communication infrastructure.
How To Fix
Latest published version: 1.163.0 as of 22 Oct 2026
pip install --upgrade "matrix-synapse==1.163.0"Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 0.33.2.10.33.2.1pip install --upgrade "matrix-synapse==0.33.2.1" -
>= 0.33.3, < 0.33.3.10.33.3.1pip install --upgrade "matrix-synapse==0.33.3.1"
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
Currently, no known workarounds exist for this vulnerability. It is essential to update the affected package to the latest secure version as soon as possible.
Conclusion
The vulnerability in Matrix Synapse before version 0.33.3.1 poses a significant risk to the integrity and confidentiality of the communication infrastructure. It is crucial to update the affected package to the latest secure version promptly. For further assistance and support in vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for matrix-synapse →
FAQ
Matrix Synapse is an open-source messaging server that facilitates secure communication and collaboration.
The vulnerability allows remote attackers to spoof events and potentially exploit other unspecified impacts, compromising the integrity and confidentiality of the communication infrastructure.
To address this vulnerability, update Matrix Synapse to version 0.33.3.1 or later.
Currently, no known workarounds exist for this vulnerability.
For more information, refer to the official GitHub advisory database: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2022/05/GHSA-fmvh-rvq5-hhjx/GHSA-fmvh-rvq5-hhjx.json
References
Related vulnerabilities
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