CVE-2021-31251 EXPLOIT
9.8
CRITICAL · CVSS 3.1 · EPSS 35.7% (pctl 98)
Patch early
A public exploit exists.
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.
Scoring
| CVSS | 9.8 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 35.71% — more likely to be exploited than 98% of all CVEs |
| Weakness | CWE-287 |
| On CISA KEV | no |
| Public exploit | yes |
| Published | 2021-06-04 |
| Last modified | 2026-06-17 |
Affected (20)
| Vendor | Product |
|---|---|
| chiyu-tech | bf-430 |
| chiyu-tech | bf-430 firmware |
| chiyu-tech | bf-431 |
| chiyu-tech | bf-431 firmware |
| chiyu-tech | bf-450m |
| chiyu-tech | bf-450m firmware |
| chiyu-tech | semac d1 |
| chiyu-tech | semac d1 firmware |
| chiyu-tech | semac d2 |
| chiyu-tech | semac d2 firmware |
| chiyu-tech | semac d2 n300 |
| chiyu-tech | semac d2 n300 firmware |
| chiyu-tech | semac d4 |
| chiyu-tech | semac d4 firmware |
| chiyu-tech | semac s1 osdp |
| chiyu-tech | semac s1 osdp firmware |
| chiyu-tech | semac s2 |
| chiyu-tech | semac s2 firmware |
| chiyu-tech | semac s3v3 |
| chiyu-tech | semac s3v3 firmware |
Public exploits
| Source | Title | Date |
|---|---|---|
| exploit-db | CHIYU IoT Devices - 'Telnet' Authentication Bypass | 2021-06-03 |
References
- https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251
- https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguU
- https://www.chiyu-tech.com/msg/message-Firmware-update-87.html
- https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251
- https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguU
- https://www.chiyu-tech.com/msg/message-Firmware-update-87.html
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