---
id: CVE-2024-52805
aliases:
  - GHSA-rfq8-j7rh-8hf2
  - PYSEC-2026-1613
title: Synapse allows unsupported content types to lead to memory exhaustion
summary: Synapse allows unsupported content types to lead to memory exhaustion
severity: high
vendor: matrix-synapse
product: matrix-synapse
ecosystem: pip
affected:
  - matrix-synapse < 1.120.1
patched:
  - matrix-synapse 1.120.1
published: '2024-12-03'
updated: '2026-07-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-rfq8-j7rh-8hf2'
references:
  - url: >-
      https://github.com/element-hq/synapse/security/advisories/GHSA-rfq8-j7rh-8hf2
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2024-52805'
  - url: 'https://github.com/twisted/twisted/issues/4688#issuecomment-1167705518'
  - url: 'https://github.com/twisted/twisted/issues/4688#issuecomment-2385711609'
  - url: 'https://github.com/element-hq/synapse'
tags:
  - osv
  - pip
epss: 0.00739
epssPercentile: 0.52544
ingestedAt: '2026-07-08T18:25:52.709Z'
---

## Overview

### Impact

In Synapse before 1.120.1, `multipart/form-data` requests can in certain configurations transiently increase memory consumption beyond expected levels while processing the request, which can be used to amplify denial of service attacks.

### Patches

Synapse 1.120.1 resolves the issue by denying requests with unsupported `multipart/form-data` content type.

### Workarounds

Limiting request sizes or blocking the `multipart/form-data` content type before the requests reach Synapse, for example in a reverse proxy, alleviates the issue. Another approach that mitigates the attack is to use a low `max_upload_size` in Synapse.

### References

- https://github.com/twisted/twisted/issues/4688#issuecomment-1167705518
- https://github.com/twisted/twisted/issues/4688#issuecomment-2385711609

### For more information

If you have any questions or comments about this advisory, please email us at [security at element.io](mailto:security@element.io).


## Affected packages

- `matrix-synapse < 1.120.1`

## Remediation

Upgrade to a patched release:

- `matrix-synapse 1.120.1`