What is CVE-2021-31643?

CVE-2021-31643 is a medium-severity vulnerability in Chiyu-Tech Bf-630, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-06-01.

How severe is CVE-2021-31643?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Chiyu-Tech Bf-630

CVE-2021-31643

An XSS vulnerability exists in several IoT devices from CHIYU Technology, including SEMAC, Biosense, BF-630, BF-631, and Webpass due to a lack of sanitization on the component if.cgi - username parameter.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-06-01 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.884 (99.8th percentile), scored 2026-10-26.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.884 · newest: 0.884 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-… (Exploit, Third Party Advisory)
www.chiyu-tech.com/msg/message-Firmware-update-87.html (Vendor Advisory)
gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices (Exploit, Third Party Advisory)
packetstormsecurity.com/files/162887/CHIYU-IoT-Cross-Site-Scripting.html (Exploit, VDB Entry, Third Party Advisory)

Frequently asked questions

What is CVE-2021-31643?: CVE-2021-31643 is a medium-severity vulnerability in Chiyu-Tech Bf-630, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-06-01.
How severe is CVE-2021-31643?: Medium severity. CVSS v3 base score is 5.4 out of 10.