CVE-2021-24476Network attack vector

Authenticated stored XSS via unsanitized group address

Published Aug 2, 2021 · Updated Aug 3, 2024

Stored XSS in Florian Chapon Steam Group Viewer 2.1 and earlier allows remote authenticated users to inject script via a group address. The plugin stores the Steam Group Address setting without sanitization and later outputs it into a page without escaping. An authenticated user who can change that setting can persist script that executes when another user loads the affected page, enabling browser-context data access or actions.

CVSS severity5.4
Medium
EPSS probability0.62%
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 Florian Chapon Steam Group Viewer 2.1 and earlier allows remote authenticated users to inject script via a group address. The plugin stores the Steam Group Address setting without sanitization and later outputs it into a page without escaping. An authenticated user who can change that setting can persist script that executes when another user loads the affected page, enabling browser-context data access or actions.

The record

CVE
CVE-2021-24476
Published
Aug 2, 2021
Updated
Aug 3, 2024
Vendor
Florian Chapon
Product
Steam Group Viewer
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 2, 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=2.1 <=2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Florian Chapon · Steam Group Viewerversion=2.1 <=2.1

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/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
Privilegesauthenticated
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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