// For flags

CVE-2024-53863

Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders

Severity Score

8.2
*CVSS v4

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Attend
*SSVC
Descriptions

Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools like Ghostscript for processing. This significantly expands the attack surface in a historically vulnerable area, presenting a risk that far outweighs the benefit, particularly since these formats are rarely used on the open web or within the Matrix ecosystem. Synapse 1.120.1 addresses the issue by restricting thumbnail generation to images in the following widely used formats: PNG, JPEG, GIF, and WebP. This vulnerability is fixed in 1.120.1.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
System
Vulnerable | Subsequent
Confidentiality
None
None
Integrity
High
None
Availability
None
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High
Attack Vector
Network
Attack Complexity
Medium
Authentication
None
Confidentiality
Partial
Integrity
None
Availability
Partial
* Common Vulnerability Scoring System
SSVC
  • Decision:Attend
Exploitation
None
Automatable
Yes
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-11-22 CVE Reserved
  • 2024-12-03 CVE Published
  • 2024-12-03 CVE Updated
  • 2025-03-30 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-434: Unrestricted Upload of File with Dangerous Type
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Element-hq
Search vendor "Element-hq"
 Synapse
Search vendor "Element-hq" for product "Synapse"
 < 1.120.1
Search vendor "Element-hq" for product "Synapse" and version " < 1.120.1"
en
Affected