CVE-2024-56828Public exploitNetwork attack vector

Authenticated arbitrary file upload via avatar suffix

Published Jan 6, 2025 · Updated Jan 14, 2025

Unrestricted file upload in ChestnutCMS 1.5.0 and earlier allows remote authenticated users to write attacker-chosen files to the server. The /api/member/avatar endpoint passes the Base64 data URI to memberService.uploadAvatarByBase64, which uses its unvalidated media subtype as a filename extension and writes the decoded bytes. Any member account can therefore store HTML, JSP, executable, or other dangerous content under the avatar upload directory, although execution depends on server handling.

CVSS severity9.8
Critical
EPSS probability0.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in ChestnutCMS 1.5.0 and earlier allows remote authenticated users to write attacker-chosen files to the server. The /api/member/avatar endpoint passes the Base64 data URI to memberService.uploadAvatarByBase64, which uses its unvalidated media subtype as a filename extension and writes the decoded bytes. Any member account can therefore store HTML, JSP, executable, or other dangerous content under the avatar upload directory, although execution depends on server handling.

The record

CVE
CVE-2024-56828
Published
Jan 6, 2025
Updated
Jan 14, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1105
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 6, 2025CVE publishedPublication date reported by the CVE source.
  2. Jan 14, 2025Record 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

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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-434Unrestricted Upload of File with Dangerous Type
T1105Ingress Tool Transfer

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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