CVE-2021-31642

Exp

A denial of service condition exists after an integer overflow in several IoT devices from CHIYU Technology, including BIOSENSE, Webpass, and BF-630, BF-631, and SEMAC. The vulnerability can be explored by sending an unexpected integer (> 32 bits) on the page parameter that will crash the web portal and making it unavailable until a reboot of the device.

Published: 2021-06-01 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31642 is rated High Exploit Risk (69.5/100): CVSS Medium severity, with high exploitation likelihood (EPSS 21.35%, 96th percentile). 4 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-31642

EDB-ID Source Kind Published Link
49937 exploit_db edb 2021-06-03 Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-31642

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-18 30.21% 21.35% -8.86%
2 2025-11-21 14.02% 30.21% +16.19%
3 2025-11-18 — 14.02% —

Full EPSS history (24 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31642

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:L/Au:S/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
 8.0 6.9 [email protected]

Weakness enumeration for CVE-2021-31642

Affected software / configurations for CVE-2021-31642

Vendor Product Version Raw CPE
chiyu-tech semac_s2_firmware — cpe:2.3:o:chiyu-tech:semac_s2_firmware:-:*:*:*:*:*:*:*
chiyu-tech semac_d1_firmware — cpe:2.3:o:chiyu-tech:semac_d1_firmware:-:*:*:*:*:*:*:*
chiyu-tech semac_d2_firmware — cpe:2.3:o:chiyu-tech:semac_d2_firmware:-:*:*:*:*:*:*:*
chiyu-tech semac_d4_firmware — cpe:2.3:o:chiyu-tech:semac_d4_firmware:-:*:*:*:*:*:*:*
chiyu-tech semac_s3v3_firmware — cpe:2.3:o:chiyu-tech:semac_s3v3_firmware:-:*:*:*:*:*:*:*
chiyu-tech semac_d2_n300_firmware — cpe:2.3:o:chiyu-tech:semac_d2_n300_firmware:-:*:*:*:*:*:*:*
chiyu-tech semac_s1_osdp_firmware — cpe:2.3:o:chiyu-tech:semac_s1_osdp_firmware:-:*:*:*:*:*:*:*
chiyu-tech bf-631_firmware — cpe:2.3:o:chiyu-tech:bf-631_firmware:-:*:*:*:*:*:*:*
chiyu-tech bf-630_firmware — cpe:2.3:o:chiyu-tech:bf-630_firmware:-:*:*:*:*:*:*:*
chiyu-tech webpass_firmware — cpe:2.3:o:chiyu-tech:webpass_firmware:-:*:*:*:*:*:*:*
chiyu-tech biosense_firmware — cpe:2.3:o:chiyu-tech:biosense_firmware:-:*:*:*:*:*:*:*

References for CVE-2021-31642

cvelogic Threat Intelligence