CVE-2021-4254Network attack vector

Stored cross-site scripting via unescaped notice text

Published Dec 18, 2022 · Updated Apr 15, 2025

Stored cross-site scripting in Ctrlo Lenio before 2021-02-08 allows remote authenticated users to run script in another user's browser. The views/layouts/main.tt template renders notice.notice.text into a notice alert without HTML escaping; the fix adds the Template Toolkit html filter. An account able to supply notice text can persist markup that executes when another user views the affected notice, enabling actions within that browser session.

CVSS severity3.5
Low
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Ctrlo Lenio before 2021-02-08 allows remote authenticated users to run script in another user's browser. The views/layouts/main.tt template renders notice.notice.text into a notice alert without HTML escaping; the fix adds the Template Toolkit html filter. An account able to supply notice text can persist markup that executes when another user views the affected notice, enabling actions within that browser session.

The record

CVE
CVE-2021-4254
Published
Dec 18, 2022
Updated
Apr 15, 2025
Vendor
Ctrlo
Product
Lenio
Classifications
CWE-707, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 18, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record 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=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Ctrlo · Lenioversion=n/a

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
3.5VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-707Improper Neutralization
T1059.007Command and Scripting Interpreter: JavaScript

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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