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.

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 like Ghostscript for processing. This significantly expands the attack surface in a historically vulnerable area, presenting a risk that far outweighs the benefit, particularly since these formats are rarely used on the open web or within the Matrix ecosystem. Synapse 1.120.1 addresses the issue by restricting thumbnail generation to images in the following widely used formats: PNG, JPEG, GIF, and WebP. This vulnerability is fixed in 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 1.120.1 rejects such invalid invites received over federation and restores the ability to sync for affected users.

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.

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 frozen in a future release, closing the attack vector.

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, but does limit an unauthenticated user's ability to request large amounts of data to be cached.

Element is a Matrix web client built using the Matrix React SDK. A malicious homeserver can send invalid messages over federation which can prevent Element Web and Desktop from rendering single messages or the entire room containing them. This was patched in Element Web and Desktop 1.11.85.

Element is a Matrix web client built using the Matrix React SDK. Versions of Element Web and Desktop earlier than 1.11.85 do not check if thumbnails for attachments, stickers and images are coherent. It is possible to add thumbnails to events trigger a file download once clicked. Fixed in element-web 1.11.85.

Element is a Matrix web client built using the Matrix React SDK. Element Web versions 1.11.70 through 1.11.80 contain a vulnerability which can, under specially crafted conditions, lead to the access token becoming exposed to third parties. At least one vector has been identified internally, involving malicious widgets, but other vectors may exist. Note that despite superficial similarity to CVE-2024-47771, this is an entirely separate vulnerability, caused by a separate piece of code included only in Element Web. Element Web and Element Desktop share most but not all, of their code and this vulnerability exists in the part of the code base which is not shared between the projects. Users are strongly advised to upgrade to version 1.11.81 to remediate the issue. As a workaround, avoid granting permissions to untrusted widgets.

Element Desktop is a Matrix client for desktop platforms. Element Desktop versions 1.11.70 through 1.11.80 contain a vulnerability which can, under specially crafted conditions, lead to the access token becoming exposed to third parties. At least one vector has been identified internally, involving malicious widgets, but other vectors may exist. Users are strongly advised to upgrade to version 1.11.81 to remediate the issue. As a workaround, avoid granting permissions to untrusted widgets.