CVE-2021-24437Public exploitNetwork attack vector

Administrator-session script execution via unescaped callback URL

Published Aug 30, 2021 · Updated Aug 3, 2024

Reflected XSS in Favicon by RealFaviconGenerator 1.3.20 and earlier allows remote attackers to run script in an administrator's browser. The Appearance-page handler returns the json_result_url query parameter in its HTML response without sanitizing or escaping it. Exploitation requires a logged-in administrator to open a crafted URL, and the injected script runs with that administrator's site origin and session authority.

CVSS severity6.1
Medium
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Favicon by RealFaviconGenerator 1.3.20 and earlier allows remote attackers to run script in an administrator's browser. The Appearance-page handler returns the json_result_url query parameter in its HTML response without sanitizing or escaping it. Exploitation requires a logged-in administrator to open a crafted URL, and the injected script runs with that administrator's site origin and session authority.

The record

CVE
CVE-2021-24437
Published
Aug 30, 2021
Updated
Aug 3, 2024
Vendor
RealFaviconGenerator
Product
Favicon by RealFaviconGenerator
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 30, 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=1.3.20 <=1.3.20

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

RealFaviconGenerator · Favicon by RealFaviconGeneratorversion=1.3.20 <=1.3.20

Published CVSS scores

6.1INCIBE-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3INCIBE-CERTAV:N/AC:M/Au:N/C:N/I:P/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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

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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