CVE-2023-42453

Publication date 27 September 2023

Last updated 23 April 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

4.3 · Medium

Score breakdown

Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Users were able to forge read receipts for any event (if they knew the room ID and event ID). Note that the users were not able to view the events, but simply mark it as read. This could be confusing as clients will show the event as read by the user, even if they are not in the room. This issue has been patched in version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.

Read the notes from the security team

Status

Package Ubuntu Release Status
matrix-synapse 24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic Ignored end of life, was needs-triage
23.04 lunar Ignored end of life, was needs-triage
22.04 LTS jammy
20.04 LTS focal Ignored patch infeasible
18.04 LTS bionic Ignored patch infeasible
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Ignored end of standard support

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Notes

john-breton

The vulnerable code is in ‘v1’ in bionic and ‘v2_alpha’ in focal, which does not appear to be called during execution. Unfortunately, this early code is incomplete, and the code needed to fix the vulnerability simply does not exist, making a backport to bionic or focal infeasible.

Severity score breakdown

Parameter Value
Base score 4.3 · Medium
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact Low
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N