← Vulnerability feed

Vulnerability record · CVE-2021-31251 · published 4 June 2021

CVE-2021-31251: Chiyu-tech bf-430 firmware improper authentication vulnerability

CChiyu Tech · Bf 430 Firmware

An authentication bypass in telnet server in BF-430 and BF431 232/422 TCP/IP Converter, BF-450M and SEMAC from CHIYU Technology Inc allows obtaining a privileged connection with the target device by supplying a specially malformed request and an attacker may force the remote telnet server to believe that the user has already authenticated.

9.8 CVSS 3.1 Critical EPSS 36% · top 1.6% CWE-287 · Improper authentication
9.8CVSS 3.1 base score, v2 7.5
36%EPSS exploitation probability, 30 days
NoNot in CISA KEV
10Affected product versions listed by NVD
6References, 4 tagged exploit
17 Jun 2026Last modified by NVD

Description

An authentication bypass in telnet server in BF-430 and BF431 232/422 TCP/IP Converter, BF-450M and SEMAC from CHIYU Technology Inc allows obtaining a privileged connection with the target device by supplying a specially malformed request and an attacker may force the remote telnet server to believe that the user has already authenticated.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

10 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251 ExploitThird Party Advisory
https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguU ExploitThird Party Advisory
https://www.chiyu-tech.com/msg/message-Firmware-update-87.html Vendor Advisory
https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251 ExploitThird Party Advisory
https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguU ExploitThird Party Advisory
https://www.chiyu-tech.com/msg/message-Firmware-update-87.html Vendor Advisory

Track CVE-2021-31251 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

6.5CVE-2021-31249Chiyu-tech bf-430 firmware injection vulnerabilityA CRLF injection vulnerability was found on BF-430, BF-431, and BF-450M TCP/IP Converter devices from CHIYU Technology Inc due to a lack of validatio…EPSS 18%6.5CVE-2021-31642Chiyu-tech semac s2 firmware integer overflow vulnerabilityA denial of service condition exists after an integer overflow in several IoT devices from CHIYU Technology, including BIOSENSE, Webpass, and BF-630,…EPSS 44%6.1CVE-2021-31252Chiyu-tech bf-430 firmware open redirect vulnerabilityAn open redirect vulnerability exists in BF-630, BF-450M, BF-430, BF-431, BF631-W, BF830-W, Webpass, and SEMAC devices from CHIYU Technology that can…EPSS 29%6.1CVE-2021-31641Chiyu-tech bf-430 firmware cross-site scripting vulnerabilityAn unauthenticated XSS vulnerability exists in several IoT devices from CHIYU Technology, including BF-630, BF-450M, BF-430, BF-431, BF631-W, BF830-W…EPSS 5.1%5.4CVE-2021-31250CHIYU TCP/IP Converter Web CGI Stored XSSCHIYU BF-430, BF-431 and BF-450M TCP/IP converter devices fail to sanitize input in the man.cgi, if.cgi, dhcpc.cgi and ppp.cgi components, allowing s…EPSS 80%analysed5.4CVE-2021-31643CHIYU IoT devices stored XSS in if.cgi username parameterSeveral CHIYU Technology IoT devices (SEMAC, Biosense, BF-630, BF-631, Webpass) fail to sanitize the username parameter in if.cgi, allowing cross-sit…EPSS 88%analysed7.5CVE-2026-42018JFrog Artifactory improper authentication leaks anonymous tokenJFrog Artifactory can return an internal anonymous-user token to an unauthenticated caller even when anonymous access is disabled. Because the token …KEVEPSS 9.8%analysed9.8CVE-2026-82329JFrog Artifactory improper authentication allows admin takeoverJFrog Artifactory contains an improper authentication weakness (CWE-287) that, under default configuration, may let an unauthenticated attacker with …KEVEPSS 14%analysed

Source: NIST National Vulnerability Database (record CVE-2021-31251), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.