Denial of Service (DoS)

Affecting matrix-synapse package, versions [0.99.0, 1.25.0rc1)

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Overview

matrix-synapse is an ecosystem for open federated Instant Messaging and VoIP.

Affected versions of this package are vulnerable to Denial of Service (DoS). A malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver. This affects any server which accepts federation requests from untrusted servers.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade matrix-synapse to version 1.25.0rc1 or higher.

References

CVSS Score

4.3
medium severity
  • Attack Vector
    Network
  • Attack Complexity
    Low
  • Privileges Required
    None
  • User Interaction
    Required
  • Scope
    Unchanged
  • Confidentiality
    None
  • Integrity
    None
  • Availability
    Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Credit
Unknown
CVE
CVE-2021-21274
CWE
CWE-400
Snyk ID
SNYK-PYTHON-MATRIXSYNAPSE-1080612
Disclosed
28 Feb, 2021
Published
28 Feb, 2021