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.
Published 2023-06-06 19:15:12
Updated 2023-06-17 03:15:09
Source GitHub, Inc.
View at NVD,
Vulnerability category: Server-side request forgery (SSRF)

Exploit prediction scoring system (EPSS) score for CVE-2023-32683

Probability of exploitation activity in the next 30 days EPSS Score History
~ 27 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2023-32683

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
GitHub, Inc.

CWE ids for CVE-2023-32683

  • The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
    Assigned by: (Primary)
  • The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
    Assigned by: (Secondary)

References for CVE-2023-32683

Products affected by CVE-2023-32683

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