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CVE-2024-53863— Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders

Quick assessment

Affected
element-hq synapse
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Element Synapse是Element开源的一个开源 Matrix 家庭服务器实现。 Element Synapse存在安全漏洞，该漏洞源于启用 dynamic_thumbnails 选项或处理特制请求可能会触发对不常见图像格式的解码和缩略图生成。

AI Predicted 8.6 Difficulty: Hard EPSS 0.62% · P47

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2024-53863

Vulnerability Information
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Vulnerability Title
Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
危险类型文件的不加限制上传
Source: CVE Program / CVE List V5
Vulnerability Title
Element Synapse 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Element Synapse是Element开源的一个开源 Matrix 家庭服务器实现。 Element Synapse存在安全漏洞，该漏洞源于启用 dynamic_thumbnails 选项或处理特制请求可能会触发对不常见图像格式的解码和缩略图生成。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
element-hq synapse < 1.120.1 -

II. Public POCs for CVE-2024-53863

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III. Intelligence Information for CVE-2024-53863

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Vendor Advisories for CVE-2024-53863 (1)

Same Patch Batch · element-hq · 2024-12-03 · 6 CVEs total

CVE-2024-37302 7.5 HIGH Synapse denial of service through media disk space consumption
CVE-2024-37303 5.3 MEDIUM Synapse unauthenticated writes to the media repository allow planting of problematic conte
CVE-2024-53867 4.3 MEDIUM Synapse Matrix has a partial room state leak via Sliding Sync
CVE-2024-52815 Synapse allows a a malformed invite to break the invitee's `/sync`
CVE-2024-52805 Synapse allows unsupported content types to lead to memory exhaustion

IV. Related Vulnerabilities

Same product: synapse
Same vendor: element-hq
Same weakness: CWE-434

V. Comments for CVE-2024-53863

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