GHSA-98px-6486-j7qc

Dashboard / Vulnerabilities / GHSA-98px-6486-j7qc

GHSA-98px-6486-j7qc

Summary: Synapse has URL deny list bypass via oEmbed and image URLs when generating previews

Details: ### 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.

References: https://github.com/matrix-org/synapse/security/advisories/GHSA-98px-6486-j7qc, https://nvd.nist.gov/vuln/detail/CVE-2023-32683, https://github.com/matrix-org/synapse/pull/15601, https://github.com/matrix-org/synapse, https://github.com/matrix-org/synapse/releases/tag/v1.85.0, https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-85.yaml, https://lists.fedoraproject.org/archives/list/[email protected]/message/X6DH5A5YEB5LRIPP32OUW25FCGZFCZU2