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Fencer Vulns
high 8.7

CVE-2021-4463 json

Longjing Technology BEMS API <= 1.21 Remote Arbitrary File Download

published 2025-11-12 11 mo ago modified 2026-06-17 4 mo ago also EUVD-2021-34715

cvss
8.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known, plus a Nuclei check

Summary

Longjing Technology BEMS API versions up to and including 1.21 contains an unauthenticated arbitrary file download vulnerability in the 'downloads' endpoint. The 'fileName' parameter is not properly sanitized, allowing attackers to craft traversal sequences and access sensitive files outside the intended directory.

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
11 mo ago

Exploit prediction

1.54% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Longjing Technology BEMS API 1.21 - Unauthenticated Arbitrary File Download nuclei detection template
  • zeroscience.mk https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-5657.php referenced PoC, tagged "exploit" by a source, unverified
  • exploit-db.com https://www.exploit-db.com/exploits/50163 referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com https://packetstormsecurity.com/files/163702 referenced PoC, tagged "exploit" by a source, unverified
  • cxsecurity.com https://cxsecurity.com/issue/WLB-2021070173 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • Shenzhen Longjing Technology Co. Ltd. BEMS API

Classification

Weakness
  • CWE-552 Files or Directories Accessible to External Parties
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.