Unauthenticated File Download Vulnerability in Longjing Technology BEMS API
CVE-2021-4463

8.7HIGH

Key Information:

Vendor

Shenzhen Longjing Technology Co. Ltd.

Status
Bems Api
Vendor
CVE Published:
12 November 2025

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2021-4463?

The BEMS API by Longjing Technology exhibits a significant security flaw in its 'downloads' endpoint, where the 'fileName' parameter is inadequately sanitized. This oversight enables attackers to create crafted traversal sequences, potentially allowing unauthorized access to sensitive files stored outside the designated directory. This vulnerability underscores the importance of proper input validation and the need to secure endpoints against arbitrary file downloads, protecting data confidentiality and system integrity.

Affected Version(s)

BEMS API 0 <= 1.21

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2021-4463 - Proof of Concept

CVE-2021-4463 - Proof of Concept

CVE-2021-4463 - Proof of Concept

References

https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-56...
technical-descriptionexploit
https://www.exploit-db.com/exploits/50163
exploit
https://packetstormsecurity.com/files/163702
exploit

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Gjoko Krstic of Zero Science Lab
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CVE-2021-4463 : Unauthenticated File Download Vulnerability in Longjing Technology BEMS API