CVE-2022-24307Network attack vector

Remote user impersonation via uncompacted signed JSON-LD

Published Feb 3, 2022 · Updated Aug 3, 2024

Incorrect authorization in Mastodon before 3.3.2 and 3.4.0 through 3.4.5 allows remote attackers to impersonate remote users. Incoming signed JSON-LD activities are processed without compaction, so crafted compact fields can collide with expanded fields and overlay different ActivityPub event content after signature validation. The ActivityPub endpoint is remotely reachable without authentication, and a successful request attributes attacker-chosen activity to another remote actor.

CVSS severity9.8
Critical
EPSS probability1.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Mastodon before 3.3.2 and 3.4.0 through 3.4.5 allows remote attackers to impersonate remote users. Incoming signed JSON-LD activities are processed without compaction, so crafted compact fields can collide with expanded fields and overlay different ActivityPub event content after signature validation. The ActivityPub endpoint is remotely reachable without authentication, and a successful request attributes attacker-chosen activity to another remote actor.

The record

CVE
CVE-2022-24307
Published
Feb 3, 2022
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-863, T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 3, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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-863Incorrect Authorization
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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