CVE-2023-32683

LOW3.5EPSS 0.27%

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

Published: 6/6/2023Modified: 9/30/2024
Also known as:GHSA-98px-6486-j7qcDEBIAN-CVE-2023-32683PYSEC-2023-85

Description

### 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.

Affected packages (3)

CVSS scores

SourceVersionSeverityVector
osvCVSS 4.0—CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
osvCVSS 3.1LOW3.5CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N

References (8)