The remote Ubuntu 18.04 ESM host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-6076-1 advisory.
– Matrix Synapse before 0.28.1 is prone to a denial of service flaw where malicious events injected with depth = 2^63 – 1 render rooms unusable, related to federation/federation_base.py and handlers/message.py, as exploited in the wild in April 2018. (CVE-2018-10657)
– The on_get_missing_events function in handlers/federation.py in Matrix Synapse before 0.31.1 has a security bug in the get_missing_events federation API where event visibility rules were not applied correctly. (CVE-2018-12291)
– In Synapse before 0.31.2, unauthorised users can hijack rooms when there is no m.room.power_levels event in force. (CVE-2018-12423)
– Matrix Synapse before 0.33.3.1 allows remote attackers to spoof events and possibly have unspecified other impacts by leveraging improper transaction and event signature validation. (CVE-2018-16515)
– An issue was discovered in Matrix Sydent before 1.0.3 and Synapse before 0.99.3.1. Random number generation is mishandled, which makes it easier for attackers to predict a Sydent authentication token or a Synapse random ID. (CVE-2019-11842)
– Matrix Synapse before 1.5.0 mishandles signature checking on some federation APIs. Events sent over /send_join, /send_leave, and /invite may not be correctly signed, or may not come from the expected servers. (CVE-2019-18835)
– Matrix Synapse before 0.34.0.1, when the macaroon_secret_key authentication parameter is not set, uses a predictable value to derive a secret key and other secrets which could allow remote attackers to impersonate users. (CVE-2019-5885)
Note that Nessus has not tested for these issues but has instead relied only on the application’s self-reported version number.Read More