CVE-2021-31251

CRITICAL
9.8
CVSS Score
Published: June 4, 2021 at 08:25 PM UTC
Updated: June 17, 2026 at 03:51 AM UTC
20 products affected across 1 vendorSemac S1 Osdp FirmwareBf 431 FirmwareBf 450M Firmware

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Severity
CRITICAL9.8
Exploit prediction
EPSS 36%

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions
chiyu-tech-bf-430 (same device)
All versions
chiyu-tech-bf-431 (same device)
All versions
chiyu-tech-bf-450m (same device)
All versions
chiyu-tech-semac-d1 (same device)
All versions
chiyu-tech-semac-d2 (same device)
All versions
chiyu-tech-semac-d2-n300 (same device)
All versions
chiyu-tech-semac-d4 (same device)
All versions
chiyu-tech-semac-s1-osdp (same device)
All versions
chiyu-tech-semac-s2 (same device)
All versions
chiyu-tech-semac-s3v3 (same device)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-287

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