https://cve.radiocsirt.org/rss/recent/all/10 Most recent entries from all 2026-10-07T20:56:05.128107+00:00 Vulnerability-Lookup csirt@opendfir.org python-feedgen Contains only the most 10 recent entries. https://cve.radiocsirt.org/vuln/cve-2023-32683 CVE-2023-32683 — URL deny list bypass via oEmbed and image URLs when generating previews in Synapse 2026-10-07T20:56:05.129785+00:00

Affected: matrix-org synapse

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.

 https://cve.radiocsirt.org/vuln/ghsa-98px-6486-j7qc GHSA-98px-6486-j7qc — Synapse has URL deny list bypass via oEmbed and image URLs when generating previews 2026-10-07T20:56:05.129843+00:00

Affected: PyPI: matrix-synapse

### Impact 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:

* For discovered oEmbed URLs, any non-JSON response or a JSON response which includes non-oEmbed information is discarded. * 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.

Because of the uncommon configuration required, the limited information a malicious user, and the amount of guesses/time the attack would need; the severity is rated as low.

### Patches

The issue is fixed by #15601.

### Workarounds

The default configuration of the `url_preview_ip_range_blacklist` should protect against requests being made to internal infrastructure, URL previews of public URLs is expected.

Alternately URL previews could be disabled using the `url_preview_enabled` setting.