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Vulnerability Analysis
URL deny list bypass via oEmbed and image URLs when generating previews in Synapse

CVE-2023-32683

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.

No Active Exploit Signals
CVSS Base Score
3.5
LOW
Exploitability:2.1
Impact Score:1.5
Temporal Score:-
EPSS:0.60%

Threat Intelligence Signals

CISA KEV
No
KEV Date Added
Ransomware Use
KEV Due Date
VulnCheck In-the-Wild
No
Nuclei Template
No
EPSS Score
0.605%
EPSS Percentile
44.3th pct
GitHub Severity
MODERATE
SSVC Exploitation
SSVC Automatable
Vulnerability Class

Identity & Timeline

Status-
Assigning Authority-
Discovered Via-
Record Completeness-
CVSS Version / Source-
Reserved-
Published-
Patch Date (date_public)-
Exploit DB Date-
First GitHub PoC Date-
Last Updated-
Time to Patch (Days to fix)-
Exploit Release Gap-
PoC Release Gap-
Exploit DB ReferencesNone identified

Affected Products & Versions

Vendor Product Affected Versions
No affected products specified.

References

No reference links found.

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