CVE-2026-24471Known exploitationNetwork attack vector

Arbitrary event forgery via unvalidated federation responses

Published Feb 2, 2026 · Updated Feb 2, 2026

Improper validation in Continuwuity before 0.5.1 allows remote attackers to obtain server-signed arbitrary Matrix events through federation. The leave, join, and knock flows accept an attacker-controlled event returned by a remote homeserver and sign it without binding it to the requested membership action. A local user must leave, join, or knock on a room that causes the victim to consult the malicious server; the leave flow enables forged messages and state events for any victim-server user.

CVSS severity9.3
Critical
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper validation in Continuwuity before 0.5.1 allows remote attackers to obtain server-signed arbitrary Matrix events through federation. The leave, join, and knock flows accept an attacker-controlled event returned by a remote homeserver and sign it without binding it to the requested membership action. A local user must leave, join, or knock on a room that causes the victim to consult the malicious server; the leave flow enables forged messages and state events for any victim-server user.

The record

CVE
CVE-2026-24471
Published
Feb 2, 2026
Updated
Feb 2, 2026
Vendor
Continuwuity
Product
Continuwuity
Classifications
CWE-20, CWE-441, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 2, 2026Record 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=< 0.5.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Continuwuity · Continuwuityversion=< 0.5.1

Published CVSS scores

9.3GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:L/SI:L/SA: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.

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
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-441Unintended Proxy or Intermediary ('Confused Deputy')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Reported exploitation

Technologies

Your stack

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Your stack

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