CVE-2021-4175Network attack vector

Stored script execution via unescaped FCM key

Published Dec 29, 2021 · Updated Aug 3, 2024

Stored XSS in Live Helper Chat 3.90 and earlier allows remote authenticated users to execute script via a crafted FCM key. The mobile settings template inserts the saved fcm_key value into an HTML input attribute without htmlspecialchars encoding. Administrative mobile-settings access is required; the payload executes in the application origin when the settings page renders.

CVSS severity6.6
Medium
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Live Helper Chat 3.90 and earlier allows remote authenticated users to execute script via a crafted FCM key. The mobile settings template inserts the saved fcm_key value into an HTML input attribute without htmlspecialchars encoding. Administrative mobile-settings access is required; the payload executes in the application origin when the settings page renders.

The record

CVE
CVE-2021-4175
Published
Dec 29, 2021
Updated
Aug 3, 2024
Vendor
LiveHelperChat
Product
Live Helper Chat
Classifications
CWE-79, T1203
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Dec 29, 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?

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

  1. Affected versionversion=unspecified <=3.90

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

LiveHelperChat · Live Helper Chatversion=unspecified <=3.90

Published CVSS scores

6.6@huntrdevCVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

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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