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Medium 6.8
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…
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Medium 5.1
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 t…
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Medium 5.3
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 o…
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Medium 5.3
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 b…
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Medium 4.3
Synapse Matrix has a partial room state leak via Sliding Sync
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 f…
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Medium 6.5
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 hi…
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Medium 5.3
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 encourag…
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Medium 4.9
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 run…
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Medium 5.4
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 T…
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Medium 6.5
Synapse Denial of service due to incorrect application of event authorization rules during state resolution
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 …
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Medium 5.0
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 ca…
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Medium 5.0
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. Syn…
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Medium 6.5
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 recoverabl…
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Medium 5.9
NULL pointer deref in signature_algorithms processing
An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a si…
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Medium 6.5
Denial of service attack via incorrect parameters to federation APIs
Matrix is an ecosystem for open federated Instant Messaging and VoIP. Synapse is a reference "homeserver" implementation of Matrix. A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the p…
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Medium 6.1
Cross-site scripting (XSS) vulnerability in the fallback authentication endpoint
AuthRestServlet in Matrix Synapse before 1.21.0 is vulnerable to XSS due to unsafe interpolation of the session GET parameter. This allows a remote attacker to execute an XSS attack on the domain Synapse is hosted on, by supplying the victim user with a malic…