---
id: CVE-2023-42453
aliases:
  - GHSA-7565-cq32-vx2x
  - PYSEC-2023-180
title: >-
  matrix-synapse vulnerable to improper validation of receipts allows forged
  read receipts
summary: >-
  matrix-synapse vulnerable to improper validation of receipts allows forged
  read receipts
severity: low
cvss: 3.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N'
vendor: matrix-synapse
product: matrix-synapse
ecosystem: pip
affected:
  - 'matrix-synapse >= 0.34.0, < 1.93.0'
patched:
  - matrix-synapse 1.93.0
published: '2023-09-26'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:49:57.892935878Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-7565-cq32-vx2x'
references:
  - url: >-
      https://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2x
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2023-42453'
  - url: 'https://github.com/matrix-org/synapse/pull/16327'
  - url: >-
      https://github.com/matrix-org/synapse/commit/63d28a88c1d18c64ea7e23b6dd7483e6d5dcf881
  - url: 'https://github.com/matrix-org/synapse'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-180.yaml
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2AFB2Y3S2VCPCN5P2XCZTG24MBMZ7DM4
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/65QPC55I4D27HIZP7H2NQ34EOXHPP4AO
  - url: >-
      https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY
  - url: 'https://security.gentoo.org/glsa/202401-12'
tags:
  - osv
  - pip
epss: 0.0065
epssPercentile: 0.49766
ingestedAt: '2026-09-12T03:13:01.669Z'
---

## Overview

### Impact
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.

### Patches
https://github.com/matrix-org/synapse/pull/16327

### Workarounds
There is no workaround.


## Affected packages

- `matrix-synapse >= 0.34.0, < 1.93.0`

## Remediation

Upgrade to a patched release:

- `matrix-synapse 1.93.0`