Client-side script execution via unsanitized error rendering
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 JavaScript through a crafted URL fragment. The public-registration route treats attacker-controlled fragment text as an undefined enum constant, then places the resulting error content into the DOM without neutralizing an encoded img onerror handler. A victim must open the attacker-supplied URL, after which the payload runs in the Cyclos origin and can read or alter browser-accessible data.
Summary
What happened
DOM-based XSS in Cyclos 4 PRO 4.14.7 and earlier allows remote attackers to execute JavaScript through a crafted URL fragment. The public-registration route treats attacker-controlled fragment text as an undefined enum constant, then places the resulting error content into the DOM without neutralizing an encoded img onerror handler. A victim must open the attacker-supplied URL, after which the payload runs in the Cyclos origin and can read or alter browser-accessible data.
The record
- CVE
- CVE-2021-31674
- Published
- May 1, 2022
- Updated
- Jul 9, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-79, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 1, 2022CVE publishedPublication date reported by the CVE source.
- Jul 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
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.
Weakness, pattern, technique
Public exploit references
- Cyclos 4.14.7 DOM-based XSS proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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