CVE-2021-3256Public exploitNetwork attack vector

Authenticated arbitrary file read via html_url

Published Jun 11, 2021 · Updated Aug 3, 2024

Arbitrary file read in KuaiFanCMS V5.x allows remote authenticated users to read server files through the html_url parameter. The chakanhtml.module.php handler accepts html_url without filtering dangerous characters, allowing crafted paths such as caches/config.php to be returned. Access requires a logged-in backend account, and the demonstrated consequence is disclosure of application configuration and other readable files without evidence of data modification or service interruption.

CVSS severity6.5
Medium
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file read in KuaiFanCMS V5.x allows remote authenticated users to read server files through the html_url parameter. The chakanhtml.module.php handler accepts html_url without filtering dangerous characters, allowing crafted paths such as caches/config.php to be returned. Access requires a logged-in backend account, and the demonstrated consequence is disclosure of application configuration and other readable files without evidence of data modification or service interruption.

The record

CVE
CVE-2021-3256
Published
Jun 11, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-88, T1005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
4.0NVDAV:N/AC:L/Au:S/C:P/I:N/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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-88Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
T1005Data from Local System

Public exploit references

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

Technologies

Your stack

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Your stack

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