PatchTheCVECVE-2021-31249: A CRLF injection vulnerability was found on BF-430, BF-431, and BF-450M TCP/IP Converter devices from CHIYU Te
CVE-2021-31249 is a medium-severity flaw (CVSS 6.5) affecting bf-430 firmware, bf-431 firmware, bf-450m firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A CRLF injection vulnerability was found on BF-430, BF-431, and BF-450M TCP/IP Converter devices from CHIYU Technology Inc due to a lack of validation on the parameter redirect= available on multiple CGI components.
Why this priority
- EPSS top 3%: very likely to be exploited
- Public exploit reference
- Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 6.5 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 18.0% (top 3%) |
| CISA exploited list | No |
| Weakness | CWE-74 |
| Published | 2021-06-04 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Public exploits and detection
Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.
- Nuclei scan template: CHIYU TCP/IP Converter - Carriage Return Line Feed Injection
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2021-31249?
bf-430 firmware: mitigate or apply the listed mitigation; bf-431 firmware: mitigate or apply the listed mitigation; bf-450m firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2021-31249 being exploited?
CVE-2021-31249 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2021-31249 affect?
CVE-2021-31249 affects bf-430 firmware, bf-431 firmware, bf-450m firmware. Severity is medium (CVSS 6.5). A CRLF injection vulnerability was found on BF-430, BF-431, and BF-450M TCP/IP Converter devices from CHIYU Technology Inc due to a lack of validation on the parameter redirect= available on multiple CGI components.
How urgent is CVE-2021-31249?
Priority 57/100. EPSS top 3%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action
Related CVEs
- CVE-2021-31641 MEDIUM 6.1 MITIGATE MITIGATE An unauthenticated XSS vulnerability exists in several IoT devices from CHIYU Technology, including BF-630, BF
- CVE-2021-31252 MEDIUM 6.1 MITIGATE MITIGATE An open redirect vulnerability exists in BF-630, BF-450M, BF-430, BF-431, BF631-W, BF830-W, Webpass, and SEMAC
- CVE-2021-31251 CRITICAL 9.8 MITIGATE MITIGATE An authentication bypass in telnet server in BF-430 and BF431 232/422 TCP/IP Converter, BF-450M and SEMAC from
- CVE-2021-31250 MEDIUM 5.4 MITIGATE MITIGATE Multiple storage XSS vulnerabilities were discovered on BF-430, BF-431 and BF-450M TCP/IP Converter devices fr
- CVE-2020-8839 MEDIUM 6.1 UPGRADE Stored XSS was discovered on CHIYU BF-430 232/485 TCP/IP Converter devices before 1.16.00, as demonstrated by