CVE-2024-53863 Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders
Attackers can force thumbnail generation of unsafe formats, potentially invoking vulnerable external decoders to execute code.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-53863?
CVE-2024-53863 is a high-severity vulnerability in element-hq synapse, published on 3 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-434
Which versions are affected by CVE-2024-53863?
3 open source packages ship an affected version, including matrix-synapse. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
matrix-synapse PyPI | All versions | 1.120.1 |
matrix-synapse PyPI | All versions | 1.120.1 |
matrix-synapse PyPI | All versions | 1.120.1 |
Products include Matrix Synapse.
How do I fix CVE-2024-53863?
Upgrade matrix-synapse to 1.120.1 or later.
Is CVE-2024-53863 being exploited?
There is no known exploitation of CVE-2024-53863 in the wild and no public exploit code.
Other vulnerabilities in element-hq synapse
- CVE-2019-18835 Improper Verification of Cryptographic Signature in matrix-synapse
- 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
- CVE-2024-37302 Synapse denial of service through media disk space consumption
- CVE-2018-12423 Matrix Synapse Authorization Error
Sources
Also known as GHSA-vp6v-whfm-rv3g, PYSEC-2026-1615, UBUNTU-CVE-2024-53863.