9.8
CRITICAL
CVE-2021-31251
Chiyu Technology Inc Telnet Server Authentication Bypass Vulnerability
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.

INFO

Published Date :

June 4, 2021, 9:15 p.m.

Last Modified :

Nov. 21, 2024, 6:05 a.m.

Remotely Exploitable :

Yes !

Impact Score :

5.9

Exploitability Score :

3.9
Affected Products

The following products are affected by CVE-2021-31251 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Chiyu-tech bf-430_firmware
2 Chiyu-tech bf-431_firmware
3 Chiyu-tech bf-450m_firmware
4 Chiyu-tech semac_s2_firmware
5 Chiyu-tech semac_d1_firmware
6 Chiyu-tech semac_d2_firmware
7 Chiyu-tech semac_d4_firmware
8 Chiyu-tech semac_s3v3_firmware
9 Chiyu-tech semac_d2_n300_firmware
10 Chiyu-tech semac_s1_osdp_firmware
11 Chiyu-tech bf-430
12 Chiyu-tech bf-431
13 Chiyu-tech bf-450m
14 Chiyu-tech semac_s2
15 Chiyu-tech semac_d1
16 Chiyu-tech semac_d2
17 Chiyu-tech semac_d4
18 Chiyu-tech semac_s3v3
19 Chiyu-tech semac_d2_n300
20 Chiyu-tech semac_s1_osdp

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-31251 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-31251 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251
    Added Reference https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguU
    Added Reference https://www.chiyu-tech.com/msg/message-Firmware-update-87.html
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • Initial Analysis by [email protected]

    Jun. 08, 2021

    Action Type Old Value New Value
    Added CVSS V2 NIST (AV:N/AC:L/Au:N/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    Changed Reference Type https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251 No Types Assigned https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31251 Exploit, Third Party Advisory
    Changed Reference Type https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguU No Types Assigned https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/#.YLqK1KhKguU Exploit, Third Party Advisory
    Changed Reference Type https://www.chiyu-tech.com/msg/message-Firmware-update-87.html No Types Assigned https://www.chiyu-tech.com/msg/message-Firmware-update-87.html Vendor Advisory
    Added CWE NIST CWE-287
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:bf-430_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:bf-430:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:bf-431_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:bf-431:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:bf-450m_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:bf-450m:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:semac_s2_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:semac_s2:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:semac_d1_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:semac_d1:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:semac_d2_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:semac_d2:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:semac_d4_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:semac_d4:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:semac_s3v3_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:semac_s3v3:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:semac_d2_n300_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:semac_d2_n300:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:chiyu-tech:semac_s1_osdp_firmware:-:*:*:*:*:*:*:* OR cpe:2.3:h:chiyu-tech:semac_s1_osdp:-:*:*:*:*:*:*:*
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-31251 is associated with the following CWEs:

Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

9.59 }} -27.62%

score

0.92118

percentile

CVSS31 - Vulnerability Scoring System
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
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Latest DB Update: Jun. 09, 2025 5:15