CVE-2021-43099Public exploitNetwork attack vector

Arbitrary file write via unchecked archive paths

Published Mar 28, 2022 · Updated Aug 4, 2024

Path traversal in diyhi bbs 5.3 allows remote authenticated users to write files outside the upgrade directory via a crafted ZIP archive. UpgradeNow in UpgradeManageAction.java passes the uploaded archive to ZipUtil.unZip without validating entry filenames or resolved paths. Administrator access to the system-upgrade function is required, and traversal entries can overwrite files reachable by the server process.

CVSS severity4.9
Medium
EPSS probability1.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Path traversal in diyhi bbs 5.3 allows remote authenticated users to write files outside the upgrade directory via a crafted ZIP archive. UpgradeNow in UpgradeManageAction.java passes the uploaded archive to ZipUtil.unZip without validating entry filenames or resolved paths. Administrator access to the system-upgrade function is required, and traversal entries can overwrite files reachable by the server process.

The record

CVE
CVE-2021-43099
Published
Mar 28, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-22
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Mar 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.9NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo