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.

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.

    It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were     tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to     cause a denial of service. (CVE-2019-18835, CVE-2018-12291, CVE-2018-10657)

    It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were     tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to     hijack the session. (CVE-2019-11842, CVE-2018-12423)

    It was discovered that Synapse incorrectly handled certain inputs. If a user or an automated system were     tricked into opening a specially crafted input file, a remote attacker could possibly use this issue to     perform

    spoofing or user impersonation. (CVE-2019-5885, CVE-2018-16515)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Fixes CVE-2018-16515

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
175821	Ubuntu 18.04 ESM : Synapse vulnerabilities (USN-6076-1)	Nessus	Ubuntu Local Security Checks	critical
120752	Fedora 29 : matrix-synapse (2018-be6e73f746)	Nessus	Fedora Local Security Checks	high
120511	Fedora 28 : matrix-synapse (2018-6db422c637)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2018-16515

high

Tenable Plugins

critical

high

high