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Unrestricted Upload of File with Dangerous Type

CVE-2024-53863

High
8.2/10

Summary

Synapse is an open-source Matrix homeserver. In Synapse versions prior to 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 addresses the issue by restricting thumbnail generation to images in the following widely used formats: "PNG," "JPEG," "GIF," and "WebP.".

  • LOW
  • NETWORK
  • HIGH
  • UNCHANGED
  • NONE
  • NONE
  • HIGH
  • NONE

CWE-434 - Unrestricted Upload of File with dangerous type

'Unrestricted file upload with dangerous type' attacks involve an attacker uploading or transferring files of dangerous types to the server. The severity of such an attack depends upon the execution mechanism and the storage location of the uploaded file. Thus, it may range from simple defacement to arbitrary file execution, and complete system takeover.

References

Advisory Timeline

  • Published