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CVE-2021-31643

65
FAUCET Score

CVE-2021-31643 is a Cross-Site Scripting (XSS) vulnerability affecting several CHIYU Technology IoT devices, including SEMAC, Biosense, BF-630, BF-631, and Webpass, stemming from insufficient sanitization of the 'username' parameter in 'if.cgi'. Rated Medium with a CVSS score of 5.4, this vulnerability requires user interaction and low privileges, allowing an attacker to achieve limited confidentiality and integrity impact. Despite its potential, there is currently no public exploit code available (Metasploit, Nuclei, ExploitDB), and it shows no signs of active exploitation or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:chiyu-tech:bf-631_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:chiyu-tech:bf-630_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:chiyu-tech:semac_s2_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:chiyu-tech:semac_d1_firmware:-:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:o:chiyu-tech:semac_d2_firmware:-:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.4MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.3
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
88.45%
Probability of exploitation in next 30 days
EPSS Percentile
99.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.8845 is in the 100th percentile among its peer group of 15,239 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

packetstormsecurity.com / files/162887/CHIYU-IoT-Cross-Site-Scripting.html
ExploitThird Party AdvisoryVDB Entry
gitbook.seguranca-informatica.pt / cve-and-exploits/cves/chiyu-iot-devices
ExploitThird Party Advisory
seguranca-informatica.pt / dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks
ExploitThird Party Advisory
chiyu-tech.com / msg/message-Firmware-update-87.html
Vendor Advisory