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TI-2023-22618 Aliases CVE-2023-42453GHSA-7565-cq32-vx2x

Improper validation of receipts allows forged read receipts in matrix synapse

Priority LOW 21CWE-285Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-285.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00777 56th percentileScored 2026-11-07
Fix Fixed synapse (matrix-org): 1.93.0matrix-synapse (PyPI): 1.93.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
matrix-orgsynapse0.34.0 to before 1.93.01.93.0Patch availableCNA
—matrix-synapse (PyPI)0.34.0 to before 1.93.01.93.0Patch availableGHSA-7565-cq32-vx2x
  • synapse Vendormatrix-org Affected 0.34.0 to before 1.93.0 Fixed in 1.93.0 Patch available CNA
  • matrix-synapse (PyPI) Vendor— Affected 0.34.0 to before 1.93.0 Fixed in 1.93.0 Patch available GHSA-7565-cq32-vx2x

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*1.34.0 to before 1.93.0Vulnerablematrix-org
cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*37VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*38VulnerableFedoraproject
  • cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* Versions 1.34.0 to before 1.93.0 Vulnerable ·matrix-org
  • cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:* Versions 37 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:* Versions 38 Vulnerable ·Fedoraproject

Remediation

  • Fix · CNA synapse (matrix-org) Fixed in 1.93.0
  • Fix · GHSA-7565-cq32-vx2x matrix-synapse (PyPI) Fixed in 1.93.0 Advisory →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2023-42453
  2. 2026-10-03 Alias added: GHSA-7565-cq32-vx2x

References

Patch 1

Advisory 2

Other 10

  • TI-2023-15617 Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites CVSS 3.1MEDIUM 5.0
  • TI-2024-35327 Synapse allows a a malformed invite to break the invitee's `/sync` CVSS 4.0HIGH 8.7
  • TI-2019-13571 Matrix Synapse before 1.5.0 mishandles signature checking on some federation APIs. CVSS 3.1CRITICAL 9.8
  • TI-2024-36056 Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders CVSS 4.0HIGH 8.2
  • TI-2024-35318 Synapse allows unsupported content types to lead to memory exhaustion CVSS 4.0HIGH 8.2
  • TI-2018-11846 Matrix Synapse before 0.33.3.1 allows remote attackers to spoof events and possibly have… CVSS 3.0HIGH 8.8
See all 39 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences