CVE-2021-31643Public exploitNetwork attack vector

Browser data theft via stored username XSS

Published Jun 1, 2021 · Updated Aug 3, 2024

Stored XSS in CHIYU Technology SEMAC, Biosense, BF-630, BF-631, and Webpass devices allows remote authenticated users to steal browser data. The if.cgi user-data handler stores the username parameter without neutralizing embedded script markup, which later executes in a viewer's browser. Exploitation requires authenticated access to submit an employee record and user interaction when that record is viewed; exposed session cookies or redirects are the bounded consequences.

CVSS severity5.4
Medium
EPSS probability88.45%
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 CHIYU Technology SEMAC, Biosense, BF-630, BF-631, and Webpass devices allows remote authenticated users to steal browser data. The if.cgi user-data handler stores the username parameter without neutralizing embedded script markup, which later executes in a viewer's browser. Exploitation requires authenticated access to submit an employee record and user interaction when that record is viewed; exposed session cookies or redirects are the bounded consequences.

The record

CVE
CVE-2021-31643
Published
Jun 1, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1539
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 1, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1539Steal Web Session Cookie

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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