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CVE-2024-53863

Matrix Synapse unrestricted file upload

9.1 CRITICALEPSS 0.61%
  1. Published3 Dec 2024

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Matrix Synapse< 1.120.1

Remediation

Fixed in
Matrix Synapse≥ 1.120.1

References

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Frequently asked

Is CVE-2024-53863 being actively exploited?

CVE-2024-53863 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.61%.

How severe is CVE-2024-53863?

CVE-2024-53863 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.61% probability of exploitation.

Which products are affected by CVE-2024-53863?

Affected products include Matrix Synapse.

How do I fix CVE-2024-53863?

Upgrade affected software to a fixed version, for example Matrix Synapse 1.120.1 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2024-53863 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.