CVE-2023-32683

Advisory

Matrix-synapse 1.85.0 includes a security fix: URL deny list bypass via oEmbed and image URLs when generating previews.
https://github.com/matrix-org/synapse/security/advisories/GHSA-98px-6486-j7qc
https://github.com/matrix-org/synapse/pull/15601

Affected package

Affected versions

Fixed versions

Vulnerability changelog

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. See CVE-2023-32683.


MISC:https://github.com/matrix-org/synapse/pull/15601: https://github.com/matrix-org/synapse/pull/15601
MISC:https://github.com/matrix-org/synapse/security/advisories/GHSA-98px-6486-j7qc: https://github.com/matrix-org/synapse/security/advisories/GHSA-98px-6486-j7qc

Resources

• https://github.com/matrix-org/synapse/pull/15601
• https://github.com/matrix-org/synapse/security/advisories/GHSA-98px-6486-j7qc
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-32683
• https://lists.fedoraproject.org/archives/list/[email protected]/message/X6DH5A5YEB5LRIPP32OUW25FCGZFCZU2/