CVE-2021-31251
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…
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 35.7%, higher than 98% of all known CVEs. Patch or mitigate before the next change window.
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
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 35.71% probability · 98th percentile
- Public exploits
- 1 in Exploit-DB · first 3 June 2021
- CISA KEV
- Not listed
- Weakness
- CWE-287
- Affected
- chiyu-tech/bf-430 firmware · chiyu-tech/bf-431 firmware · chiyu-tech/bf-450m firmware · chiyu-tech/semac s2 firmware · chiyu-tech/semac d1 firmware · chiyu-tech/semac d2 firmware · chiyu-tech/semac d4 firmware · chiyu-tech/semac s3v3 firmware · chiyu-tech/semac d2 n300 firmware · chiyu-tech/semac s1 osdp firmware
- Source
- cve@mitre.org
EPSS 35.7% since 3 November 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251Exploit, Third Party Advisory
- https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguUExploit, Third Party Advisory
- https://www.chiyu-tech.com/msg/message-Firmware-update-87.htmlVendor Advisory
- https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251Exploit, Third Party Advisory
- https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguUExploit, Third Party Advisory
- https://www.chiyu-tech.com/msg/message-Firmware-update-87.htmlVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.