CVE-2021-24535Public exploitNetwork attack vector

Stored XSS via forged settings update

Published Aug 16, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in Light Messages 1.0 and earlier allows remote attackers to inject script through a forged settings request. The settings handler accepts updates without a CSRF check and stores unsanitized Message Content even when unfiltered_html is disabled. Execution requires a logged-in administrator to submit the crafted request; the payload then runs in the settings page and, when enabled, on the front end.

CVSS severity6.1
Medium
EPSS probability0.41%
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 Light Messages 1.0 and earlier allows remote attackers to inject script through a forged settings request. The settings handler accepts updates without a CSRF check and stores unsanitized Message Content even when unfiltered_html is disabled. Execution requires a logged-in administrator to submit the crafted request; the payload then runs in the settings page and, when enabled, on the front end.

The record

CVE
CVE-2021-24535
Published
Aug 16, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-352, CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 2021CVE 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

4.3NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

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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