matrix-synapse

Vulnerabilities (44)

• CVE-2026-45076May 14, 2026
  affected < 1.152.1fixed 1.152.1

  ### Impact In federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. ### Patches Update to Synapse 1.152.1 or later. ### Workaro

• CVE-2026-45078higMay 14, 2026
  affected < 1.152.1fixed 1.152.1

  ### Impact Local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. Homeservers that trust all their local users are not at risk. ### Patches Update to Synapse 1.152.1 or later.

• CVE-2025-61672MedOct 8, 2025
  affected < 1.138.3fixed 1.138.3

  Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to

• CVE-2025-30355Mar 27, 2025
  affected < 1.127.1fixed 1.127.1

  Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1.

• CVE-2024-53867MedDec 3, 2024
  affected >= 1.113.0rc1, < 1.120.1fixed 1.120.1

  Synapse is an open-source Matrix homeserver. The Sliding Sync feature on Synapse versions between 1.113.0rc1 and 1.120.0 can leak partial room state changes to users no longer in a room. Non-state events, like messages, are unaffected. This vulnerability is fixed in 1.120.1.

• CVE-2024-37303Dec 3, 2024
  affected < 1.106fixed 1.106

  Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for

• CVE-2024-37302Dec 3, 2024
  affected < 1.106fixed 1.106

  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

• CVE-2024-52805Dec 3, 2024
  affected < 1.120.1fixed 1.120.1

  Synapse is an open-source Matrix homeserver. In Synapse before 1.120.1, multipart/form-data requests can in certain configurations transiently increase memory consumption beyond expected levels while processing the request, which can be used to amplify denial of service attacks.

• CVE-2024-52815Dec 3, 2024
  affected < 1.120.1fixed 1.120.1

  Synapse is an open-source Matrix homeserver. Synapse versions before 1.120.1 fail to properly validate invites received over federation. This vulnerability allows a malicious server to send a specially crafted invite that disrupts the invited user's /sync functionality. Synapse 1

• CVE-2024-53863Dec 3, 2024
  affected < 1.120.1fixed 1.120.1

  Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools lik

• CVE-2024-31208Apr 23, 2024
  affected < 1.105.1fixed 1.105.1

  Synapse is an open-source Matrix homeserver. A remote Matrix user with malicious intent, sharing a room with Synapse instances before 1.105.1, can dispatch specially crafted events to exploit a weakness in the V2 state resolution algorithm. This can induce high CPU consumption an

• CVE-2023-43796Oct 31, 2023
  affected < 1.95.1fixed 1.95.1

  Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Syna

• CVE-2023-45129Oct 10, 2023
  affected < 1.94.0fixed 1.94.0

  Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, a malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service. Homeservers running on a closed fede

• CVE-2023-41335Sep 26, 2023
  affected >= 1.66.0, < 1.93.0fixed 1.93.0

  Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. When users update their passwords, the new credentials may be briefly held in the server database. While this doesn't grant the server any added capabilities—it already learns the use

• CVE-2023-42453Sep 26, 2023
  affected >= 0.34.0, < 1.93.0fixed 1.93.0

  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 co

• CVE-2023-32683Jun 6, 2023
  affected < 1.85.0fixed 1.85.0

  Synapse is a Matrix protocol homeserver written in Python with the Twisted framework. A discovered oEmbed or image URL can bypass the `url_preview_url_blacklist` setting potentially allowing server side request forgery or bypassing network policies. Impact is limited to IP addres

• CVE-2023-32682Jun 6, 2023
  affected < 1.85.0fixed 1.85.0

  Synapse is a Matrix protocol homeserver written in Python with the Twisted framework. In affected versions it may be possible for a deactivated user to login when using uncommon configurations. This only applies if any of the following are true: 1. JSON Web Tokens are enabled for

• CVE-2022-39374May 26, 2023
  affected >= 1.62.0, < 1.68.0rc1fixed 1.68.0rc1

  Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. If Synapse and a malicious homeserver are both joined to the same room, the malicious homeserver can trick Synapse into accepting previously rejected events into its view of the curre

• CVE-2022-39335May 26, 2023
  affected < 1.69.0fixed 1.69.0

  Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. The Matrix Federation API allows remote homeservers to request the authorization events in a room. This is necessary so that a homeserver receiving some events can validate that those

• CVE-2023-32323May 26, 2023
  affected < 1.74.0fixed 1.74.0

  Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. A malicious user on a Synapse homeserver X with permission to create certain state events can disable outbound federation from X to an arbitrary homeserver Y. Synapse instances with f