CVE-2021-31251Bf-430 Firmware Authentication Bypass
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…
Published Jun 4, 2021 · Updated Nov 21, 2024
Key Facts
Patch immediately- CVE-2021-31251 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Bf-430 Firmware (Chiyu-Tech), Bf-431 Firmware (Chiyu-Tech), Bf-450m Firmware (Chiyu-Tech) and 7 more products.
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 36% probability of exploitation in the next 30 days.
- No fixed version is listed yet; check the vendor advisory for mitigations.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Scores
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
36%
Higher than 98.4% of all scored CVEs
Exploit maturity
Proof of concept
ATLAS score
39/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Not listed
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Proof of concept
Public exploit code
1
Proof-of-concept links
In-the-wild evidence
2
Reports of active use
Advisories And Exploit References
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.
Affected Products
10 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Bf-430 FirmwareChiyu-Tech | See advisory | n/a |
| Bf-431 FirmwareChiyu-Tech | See advisory | n/a |
| Bf-450m FirmwareChiyu-Tech | See advisory | n/a |
| Semac D1 FirmwareChiyu-Tech | See advisory | n/a |
| Semac D2 FirmwareChiyu-Tech | See advisory | n/a |
Timeline
Publicly disclosed
Jun 4, 2021
Last updated
Nov 21, 2024
Weakness Type
- CWE-287 Improper Authentication
FAQ
Common Questions.
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…
Affected: Bf-430 Firmware (Chiyu-Tech); Bf-431 Firmware (Chiyu-Tech); Bf-450m Firmware (Chiyu-Tech), among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
No fixed version is listed yet; check the vendor advisory for mitigations.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
Is CVE-2021-31251 On Your Attack Surface?
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