CVE-2024-25623Network attack vector

Remote account impersonation via unchecked response media type

Published Feb 19, 2024 · Updated Aug 1, 2024

Identity spoofing in affected Mastodon 3.5 through 4.2 releases allows remote authenticated users to impersonate remote accounts. FetchRemoteStatusService accepts fetched JSON as an Activity Streams object without verifying an Activity Streams Content-Type, then trusts a same-domain attributedTo value. Exploitation requires a low-privileged account on a remote server that permits predictable or editable same-domain document uploads and serves them for Activity Streams requests.

CVSS severity8.5
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Identity spoofing in affected Mastodon 3.5 through 4.2 releases allows remote authenticated users to impersonate remote accounts. FetchRemoteStatusService accepts fetched JSON as an Activity Streams object without verifying an Activity Streams Content-Type, then trusts a same-domain attributedTo value. Exploitation requires a low-privileged account on a remote server that permits predictable or editable same-domain document uploads and serves them for Activity Streams requests.

The record

CVE
CVE-2024-25623
Published
Feb 19, 2024
Updated
Aug 1, 2024
Vendor
Mastodon
Product
Mastodon
Classifications
CWE-434, T1036
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 19, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 1, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 3.5.19
  2. Affected versionversion=>= 4.0.0, < 4.0.15
  3. Affected versionversion=>= 4.1.0, < 4.1.15
  4. Affected versionversion=>= 4.2.0, < 4.2.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mastodon · Mastodonversion=< 3.5.19; version=>= 4.0.0, < 4.0.15; version=>= 4.1.0, < 4.1.15; version=>= 4.2.0, < 4.2.7

Published CVSS scores

7.7NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N
8.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
T1036Masquerading

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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