HOMEVULNERABILITIESCVE-2023-42453
MEDIUM

CVE-2023-42453

CWE-285Published: September 27, 2023· Updated: Jun 17, 2026

4.3
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2023-42453 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected Vendors & Products

Fedora1 product(s)
fedora
matrix1 product(s)
synapse
Source: NVD CPE · 3 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/matrix-org/synapse/pull/16327
PATCHhttps://github.com/matrix-org/synapse/pull/16327
ADVISORYhttps://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2x
ADVISORYhttps://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2x

All References (12)

→
https://github.com/matrix-org/synapse/pull/16327Issue Tracking · Patch
→
https://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2xVendor Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2AFB2Y3S2VCPCN5P2XCZTG24MBMZ7DM4/Mailing List · Release Notes
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/65QPC55I4D27HIZP7H2NQ34EOXHPP4AO/Mailing List · Release Notes
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY/
→
https://security.gentoo.org/glsa/202401-12
→
https://github.com/matrix-org/synapse/pull/16327Issue Tracking · Patch
→
https://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2xVendor Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2AFB2Y3S2VCPCN5P2XCZTG24MBMZ7DM4/Mailing List · Release Notes
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/65QPC55I4D27HIZP7H2NQ34EOXHPP4AO/Mailing List · Release Notes
→
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY/
→
https://security.gentoo.org/glsa/202401-12

Quick Facts

CVE IDCVE-2023-42453
CVSS Score4.3 / 10
SeverityMEDIUM
WeaknessCWE-285
CISA KEVNo
Affected2 vendor(s)
PublishedSep 27, 2023

Related CVEs (CWE-285)

CVE-2022-2595
10.0
CVE-2026-57983
10.0
CVE-2021-37705
10.0
CVE-2021-31384
10.0
CVE-2020-5206
10.0
CVE-2026-34048
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2023-42453 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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