CVE-2021-31673Public exploitNetwork attack vector

Script execution via unneutralized registration groupId

Published May 1, 2022 · Updated Jul 9, 2026

DOM-based XSS in Cyclos 4 PRO 4.14.7 and earlier allows remote attackers to execute script through a crafted groupId registration URL. The public-registration route treats the groupId fragment value as HTML, so an injected image element and its error handler enter the page DOM. Exploitation requires a victim to open the attacker-supplied URL; the script then runs in the Cyclos origin and can access or alter data available to that browser session.

CVSS severity6.1
Medium
EPSS probability2.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DOM-based XSS in Cyclos 4 PRO 4.14.7 and earlier allows remote attackers to execute script through a crafted groupId registration URL. The public-registration route treats the groupId fragment value as HTML, so an injected image element and its error handler enter the page DOM. Exploitation requires a victim to open the attacker-supplied URL; the script then runs in the Cyclos origin and can access or alter data available to that browser session.

The record

CVE
CVE-2021-31673
Published
May 1, 2022
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 1, 2022CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV: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')
T1204.001User Execution: Malicious Link

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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