CVE-2023-32683
URL deny list bypass via oEmbed and image URLs when generating previews in Synapse
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
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.
Timeline
ID reserved
By GitHub_M
- 26 days later
· 26 days later
Published
- 21 months later
· 21 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Low3.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N |
| NVDNVD · Modified | 3.1 | Medium5.4 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N |
- EPSS (exploitation in 30 days)
- 0.60% · top 51% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 3.5.
Weakness
Affected products
- affected < 1.85.0
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- PyPImatrix-synapseGHSA-98px-6486-j7qc (opens in a new tab)
References (3)
- https://github.com/matrix-org/synapse/security/advisories/GHSA-98px-6486-j7qc (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/matrix-org/synapse/pull/15601 (opens in a new tab)x_refsource_MISCx_transferred
- https://lists.fedoraproject.org/archives/list/[email protected]/message/X6DH5A5YEB5LRIPP32OUW25FCGZFCZU2/ (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-98px-6486-j7qc (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-32683)Record last updated .