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 encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

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 host is affected by the vulnerability described in GLSA-202401-12 (Synapse: Multiple Vulnerabilities)

  - Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. When     users update their passwords, the new credentials may be briefly held in the server database. While this     doesn't grant the server any added capabilitiesit already learns the users' passwords as part of the     authentication processit does disrupt the expectation that passwords won't be stored in the database. As     a result, these passwords could inadvertently be captured in database backups for a longer duration. These     temporarily stored passwords are automatically erased after a 48-hour window. This issue has been     addressed in version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.
    (CVE-2023-41335)

  - Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Users     were able to forge read receipts for any event (if they knew the room ID and event ID). Note that the     users were not able to view the events, but simply mark it as read. This could be confusing as clients     will show the event as read by the user, even if they are not in the room. This issue has been patched in     version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.
    (CVE-2023-42453)

  - 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 encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to     receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation     traffic with a homeserver. (CVE-2023-43796)

  - 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 running on a closed federation (which presumably do not need     to use server ACLs) are not affected. Server administrators are advised to upgrade to Synapse 1.94.0 or     later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin     API. (CVE-2023-45129)

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 39 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2023-957972e77c advisory.

    Update to 1.95.1 (CVE-2023-43796)

    ----

    Update to v1.95.0

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

Note that Nessus has not tested for this issue 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 a vulnerability as referenced in the FEDORA-2023-f8d216faed advisory.

    Update to 1.95.1 (CVE-2023-43796)

    ----

    Update to v1.95.0

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

Note that Nessus has not tested for this issue 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
187728	GLSA-202401-12 : Synapse: Multiple Vulnerabilities	Nessus	Gentoo Local Security Checks	medium
185440	Fedora 39 : matrix-synapse (2023-957972e77c)	Nessus	Fedora Local Security Checks	medium
185439	Fedora 38 : matrix-synapse (2023-f8d216faed)	Nessus	Fedora Local Security Checks	medium

Detections

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CVE-2023-43796

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Tenable Plugins

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medium

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