CVE-2024-52805Network attack vector

Service interruption via in-memory multipart parsing

Published Dec 3, 2024 · Updated Dec 3, 2024

Resource exhaustion in Element HQ Synapse before 1.120.1 allows remote attackers to interrupt service with multipart/form-data POST requests. Synapse's Twisted request path parses the entire unsupported multipart body in memory instead of rejecting its content type before dispatch. Exposure requires a high max_upload_size and no upload-limiting reverse proxy; oversized bodies can crash the process or starve other requests.

CVSS severity8.2
High
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Element HQ Synapse before 1.120.1 allows remote attackers to interrupt service with multipart/form-data POST requests. Synapse's Twisted request path parses the entire unsupported multipart body in memory instead of rejecting its content type before dispatch. Exposure requires a high max_upload_size and no upload-limiting reverse proxy; oversized bodies can crash the process or starve other requests.

The record

CVE
CVE-2024-52805
Published
Dec 3, 2024
Updated
Dec 3, 2024
Vendor
Element HQ
Product
Synapse
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 3, 2024CVE publishedPublication date reported by the CVE source.
  2. Dec 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.120.1
  2. Affected versionversion=< 1.120.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Element HQ · Synapseversion=0 <1.120.1; version=< 1.120.1

Published CVSS scores

8.2GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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