{"id":"CVE-2023-32683","aliases":["GHSA-98px-6486-j7qc","PYSEC-2023-85"],"url":"https://o3.security/vulnerability/CVE-2023-32683","summary":"URL deny list bypass via oEmbed and image URLs when generating previews in Synapse","details":"### Impact\nA 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:\n\n* For discovered oEmbed URLs, any non-JSON response or a JSON response which includes non-oEmbed information is discarded.\n* For discovered image URLs, any non-image response is discarded.\n\nSystems which have URL preview disabled (via the `url_preview_enabled` setting) or have not configured a `url_preview_url_blacklist` are not affected.\n\nBecause 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.\n\n### Patches\n\nThe issue is fixed by #15601.\n\n### Workarounds\n\nThe 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.\n\nAlternately URL previews could be disabled using the `url_preview_enabled` setting.","published":"2023-06-06T18:24:30.457Z","modified":"2026-08-12T03:51:19.554812141Z","cvss":{"score":3.5,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"matrix-synapse","fixedVersion":"1.85.0"}],"fix":{"url":"https://github.com/matrix-org/synapse/pull/15601","label":"matrix-org/synapse#15601"},"references":[{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/X6DH5A5YEB5LRIPP32OUW25FCGZFCZU2/"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/32xxx/CVE-2023-32683.json"},{"type":"ADVISORY","url":"https://github.com/matrix-org/synapse/security/advisories/GHSA-98px-6486-j7qc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-32683"},{"type":"FIX","url":"https://github.com/matrix-org/synapse/pull/15601"},{"type":"PACKAGE","url":"https://github.com/matrix-org/synapse"},{"type":"WEB","url":"https://github.com/matrix-org/synapse/releases/tag/v1.85.0"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2023-85.yaml"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/X6DH5A5YEB5LRIPP32OUW25FCGZFCZU2"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:19.554812141Z"}}