SB2020121621 - Resource exhaustion in synapse (Alpine package)

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Main Vulnerability Database SB2020121621

SB2020121621 - Resource exhaustion in synapse (Alpine package)

Published: December 16, 2020

Security Bulletin ID SB2020121621
Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Denial of service

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 security vulnerability.


1) Resource exhaustion (CVE-ID: CVE-2020-26257)

The vulnerability allows a remote authenticated user to perform a denial of service (DoS) attack.

Matrix is an ecosystem for open federated Instant Messaging and VoIP. Synapse is a reference "homeserver" implementation of Matrix. A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a `/send_join`, `/send_leave`, `/invite` or `/exchange_third_party_invite` request. This can lead to a denial of service in which future events will not be correctly sent to other servers over federation. This affects any server which accepts federation requests from untrusted servers. The Matrix Synapse reference implementation before version 1.23.1 the implementation is vulnerable to this injection attack. Issue is fixed in version 1.23.1. As a workaround homeserver administrators could limit access to the federation API to trusted servers (for example via `federation_domain_whitelist`).


Remediation

Install update from vendor's website.

References