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CVE-2024-53863

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

Published: Dec 3, 2024Updated: Aug 26, 2025 Sources: CVE List NVD GHSACWE-434
NVD MITRE
9.1CVSSCRITICAL
EPSS Score
0.6%
Top 55.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-434

Affected Products

synapsematrix
On-premWeb App
Communications / messaging-chat
matrix-synapsePyPIOSS Libraries
synapseelement-hq
Mixed
Communications / messaging-chat
matrixoss-projectGBCommunicationsaka synapse, matrix irc bridge, javascript sdk
pypipackage-ecosystemOSS Libraries
element-hqoss-projectCommunications

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

3 techniques
Command and Control
Initial Access
Persistence
View detailed technique mapping

References

https://github.com/element-hq/synapse/security/advisories/GHSA-vp6v-whfm-rv3g
github.com
https://nvd.nist.gov/vuln/detail/CVE-2024-53863
nvd.nist.gov
https://github.com/element-hq/synapse
github.com

Timeline

Published
Dec 3, 2024
Last Updated
Aug 26, 2025

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