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 preview disabled (via the `url_preview_enabled` setting) or have not configured a `url_preview_url_blacklist` are not affected. This issue has been addressed in version 1.85.0. Users are advised to upgrade. User unable to upgrade may also disable URL previews.

The remote Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-7444-1 advisory.

    It was discovered that Synapse network policies could be bypassed via specially crafted URLs. An attacker     could possibly use this issue to bypass authentication mechanisms. (CVE-2023-32683)

    It was discovered that Synapse exposed cached device information. An attacker could possibly use this     issue to gain access to sensitive information. (CVE-2023-43796)

    It was discovered that Synapse could be tricked into rejecting state changes in rooms. An attacker could     possibly use this issue to cause Synapse to stop functioning properly, resulting in a denial of service.
    This issue was only fixed in Ubuntu 20.04 LTS and Ubuntu 22.04 LTS. (CVE-2022-39374)

    It was discovered that Synapse stored user credentials in a server's database temporarily. An attacker     could possibly use this issue to gain access to sensitive information. This issue was only fixed in Ubuntu     22.04 LTS. (CVE-2023-41335)

    It was discovered that Synapse could incorrectly respond to server authorization events. An attacker could     possibly use this issue to bypass authentication mechanisms. This issue was only fixed in Ubuntu 22.04     LTS. (CVE-2022-39335)

    It was discovered that Synapse could be manipulated to mark messages as read when they had not been     viewed. An attacker could possibly use this issue to perform repudiation-based attacks. This issue was     only fixed in Ubuntu 22.04 LTS. (CVE-2023-42453)

    It was discovered that Synapse had several memory-related issues. An attacker could possibly use this     issue to cause Synapse to crash, resulting in a denial of service. This issue was only fixed in Ubuntu     22.04 LTS. (CVE-2024-31208)

    It was discovered that Synapse could run external tools due to a unchecked thumbnail rendering routine. An     attacker could possibly use this issue to cause Synapse to crash, resulting in a denial of service, or     execute arbitrary code. This issue was only fixed in Ubuntu 22.04 LTS. (CVE-2024-53863)

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.

The remote Fedora 38 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2023-56760afca8 advisory.

    Update to v1.85.2

    ----

    Update to v1.85.1

    ----

    Update to v1.85.0     Fixes CVE-2023-32682, CVE-2023-32683

    ----

    Update to v1.84.1


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

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

ID	Name	Product	Family	Severity
234734	Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS : Synapse vulnerabilities (USN-7444-1)	Nessus	Ubuntu Local Security Checks	high
177402	Fedora 38 : matrix-synapse (2023-56760afca8)	Nessus	Fedora Local Security Checks	medium

Detections

Analytics

CVE-2023-32683

medium

Tenable Plugins

high

medium