p PatchFirst

PatchFirst · Latest vulnerabilities

matrix-synapse vulnerabilities

Vulnerabilities published for matrix-synapse in the last 30 days: 0. Listed in the KEV catalogue: 0.

Filter vulnerabilities
Clear filters

Vulnerabilities: 39

  1. CVE-2026-45078

    Medium · CVSS 6.8EPSS 0.13%No fix published

    Synapse CPU starvation (Denial of Service)

    Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, 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. This vulnerability is fixed in 1.152.1.

    Published Updated
  2. CVE-2026-45076

    Medium · CVSS 5.1EPSS 0.37%No fix published

    Synapse pagination denial of service

    Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, 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. This vulnerability is fixed in 1.152.1.

    Published Updated
  3. CVE-2025-61672

    Medium · CVSS 5.3EPSS 0.48%No fix published

    Synapse: Invalid device keys degrade federation functionality

    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 other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2.

    Published Updated
  4. CVE-2025-30355

    High · CVSS 7.1EPSS 1.23%No fix published

    Synapse vulnerable to federation denial of service via malformed events

    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. No known workarounds are available.

    Published Updated
  5. CVE-2024-37303

    Medium · CVSS 5.3EPSS 0.43%No fix published

    Synapse unauthenticated writes to the media repository allow planting of problematic content

    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 download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be fro

    Published Updated
  6. CVE-2024-37302

    High · CVSS 7.5EPSS 0.6%No fix published

    Synapse denial of service through media disk space consumption

    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 this. This can lead to a denial of service, ranging from further media uploads/downloads failing to completely unavailability of the Synapse process, depending on how Synapse was deployed. Synapse 1.106 introduces a new "leaky bucket" rate limit on remote media downloads to reduce the amount of data a user can request at a time. This does not fully address the issue,

    Published Updated
  7. CVE-2024-52805

    High · CVSS 8.2EPSS 0.74%No fix published

    Synapse allows unsupported content types to lead to memory exhaustion

    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. Synapse 1.120.1 resolves the issue by denying requests with unsupported multipart/form-data content type.

    Published Updated
  8. CVE-2024-52815

    High · CVSS 8.7EPSS 0.57%No fix published

    Synapse allows a a malformed invite to break the invitee's `/sync`

    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 1.120.1 rejects such invalid invites received over federation and restores the ability to sync for affected users.

    Published Updated
  9. CVE-2024-31208

    Medium · CVSS 6.5EPSS 1.46%No fix published

    Synapse's V2 state resolution weakness allows DoS from remote room members

    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 and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge th

    Published Updated
  10. CVE-2023-43796

    Medium · CVSS 5.3EPSS 0.9%Fix available

    Synapse vulnerable to leak of remote user device information

    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 Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

    • Update to 0.24.0+dfsg-1ubuntu0.1~esm4
    Published Updated
  11. CVE-2023-45129

    Medium · CVSS 4.9EPSS 1.39%No fix published

    matrix-synapse vulnerable to denial of service due to malicious server ACL events

    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 federation (which presumably do not need to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.

    Published Updated
  12. CVE-2023-42453

    Low · CVSS 3.1EPSS 0.78%No fix published

    Improper validation of receipts allows forged read receipts in matrix synapse

    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.

    Published Updated
  13. CVE-2023-32683

    Low · CVSS 3.5EPSS 0.6%Fix available

    URL deny list bypass via oEmbed and image URLs when generating previews in Synapse

    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 addresses allowed by the `url_preview_ip_range_blacklist` setting (by default this only allows public IPs) and by the limited information returned to the client: 1. For discovered oEmbed URLs, any non-JSON response or a JSON response which includes non-oEmbed information is discarded. 2. For discovered image URLs, any non-image response is discarded. Systems which have URL

    • Update to 0.24.0+dfsg-1ubuntu0.1~esm4
    Published Updated
  14. CVE-2023-32682

    Medium · CVSS 5.4EPSS 0.75%No fix published

    Improper checks for deactivated users during login in synapse

    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 login via the `jwt_config.enabled` configuration setting. 2. The local password database is enabled via the `password_config.enabled` and `password_config.localdb_enabled` configuration settings *and* a user's password is updated via an admin API after a user is deactivated. Note that the local password database is enabled by default, but it is uncommon to set a user

    Published Updated
  15. CVE-2022-39335

    Medium · CVSS 5EPSS 0.64%No fix published

    Synapse does not apply enough checks to servers requesting auth events of events in a room

    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 events are legitimate and permitted in their room. However, in versions of Synapse up to and including 1.68.0, a Synapse homeserver answering a query for authorization events does not sufficiently check that the requesting server should be able to access them. The issue was patched in Synapse 1.69.0. Homeserver administrators are advised to upgrade.

    Published Updated
  16. CVE-2023-32323

    Medium · CVSS 5EPSS 0.98%No fix published

    Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites

    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 federation disabled are not affected. In versions of Synapse up to and including 1.73, Synapse did not limit the size of `invite_room_state`, meaning that it was possible to create an arbitrarily large invite event. Synapse 1.74 refuses to create oversized `invite_room_state` fields. Server operators should upgrade to Synapse 1.74 or newer urgently.

    Published Updated
  17. CVE-2022-41952

    Medium · CVSS 6.5EPSS 0.94%No fix published

    Uncontrolled Resource Consumption in Matrix Synapse

    Synapse before 1.52.0 with URL preview functionality enabled will attempt to generate URL previews for media stream URLs without properly limiting connection time. Connections will only be terminated after `max_spider_size` (default: 10M) bytes have been downloaded, which can in some cases lead to long-lived connections towards the streaming media server (for instance, Icecast). This can cause excessive traffic and connections toward such servers if their stream URL is, for example, posted to a large room with many Synapse instances with URL preview enabled. Version 1.52.0 implements a timeout mechanism which will terminate URL preview connec

    Published Updated
  18. CVE-2022-31152

    Medium · CVSS 6.4EPSS 1.2%No fix published

    Synapse vulnerable to denial of service (DoS) due to incorrect application of event authorization rules

    Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. The Matrix specification specifies a list of [event authorization rules](https://spec.matrix.org/v1.2/rooms/v9/#authorization-rules) which must be checked when determining if an event should be accepted into a room. In versions of Synapse up to and including version 1.61.0, some of these rules are not correctly applied. An attacker could craft events which would be accepted by Synapse but not a spec-conformant server, potentially causing divergence in the room state between servers. Administrators of homeservers with federation enabled are advised

    Published Updated
  19. CVE-2022-31052

    Medium · CVSS 6.5EPSS 1.66%No fix published

    URL previews can crash Synapse media repositories or Synapse monoliths

    Synapse is an open source home server implementation for the Matrix chat network. In versions prior to 1.61.1 URL previews of some web pages can exhaust the available stack space for the Synapse process due to unbounded recursion. This is sometimes recoverable and leads to an error for the request causing the problem, but in other cases the Synapse process may crash altogether. It is possible to exploit this maliciously, either by malicious users on the homeserver, or by remote users sending URLs that a local user's client may automatically request a URL preview for. Remote users are not able to exploit this directly, because the URL preview

    Published Updated
  20. CVE-2021-41281

    High · CVSS 7.5EPSS 1.58%No fix published

    Path traversal in Matrix Synapse

    Synapse is a package for Matrix homeservers written in Python 3/Twisted. Prior to version 1.47.1, Synapse instances with the media repository enabled can be tricked into downloading a file from a remote server into an arbitrary directory. No authentication is required for the affected endpoint. The last 2 directories and file name of the path are chosen randomly by Synapse and cannot be controlled by an attacker, which limits the impact. Homeservers with the media repository disabled are unaffected. Homeservers with a federation whitelist are also unaffected, since Synapse will check the remote hostname, including the trailing `../`s, against

    Published Updated

Check your server

Check your installed stack and versions against the current vulnerability feeds.

Check your server →