CVE-2024-37302

Publication date 3 December 2024

Last updated 30 May 2025

Ubuntu priority

Cvss 3 Severity Score

Synapse is an open-source Matrix homeserver. Synapse versions before 1.106 are vulnerable to a disk fill attack, where an unauthenticated adversary can induce Synapse to download and cache large amounts of remote media. The default rate limit strategy is insufficient to mitigate this. This can lead to a denial of service, ranging from further media uploads/downloads failing to completely unavailability of the Synapse process, depending on how Synapse was deployed. Synapse 1.106 introduces a new “leaky bucket” rate limit on remote media downloads to reduce the amount of data a user can request at a time. This does not fully address the issue, but does limit an unauthenticated user’s ability to request large amounts of data to be cached.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
matrix-synapse	24.10 oracular	Vulnerable, fix deferred
	24.04 LTS noble	Vulnerable, fix deferred
	22.04 LTS jammy	Vulnerable, fix deferred
	20.04 LTS focal	Vulnerable, fix deferred
	18.04 LTS bionic	Vulnerable, fix deferred

Notes

john-breton

As of 7/4/2025 no patch for this CVE exists. It may be possible to extract the fix from 1.116.0-1 source, but such an undertaking would require significant effort.

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H