VulnerabilityPublished 6 Jan 2025Updated 14 Jan 2025

CVE-2024-56828: ChestnutCMS · File Upload

Affects ChestnutCMSSource CVE Database V5

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 12:54 UTC

CVSS 3.1 base score

9.8Critical

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.9% chance of exploitation in 30 days – higher than 59% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Jan 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
GitHubliweiyi/ChestnutCMS`pkg:github/liweiyi/ChestnutCMS`Other threats	Affected <=1.5.0	Fixed in–

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AI-suggested

To mitigate CVE-2024-56828, organizations should immediately implement the following measures: 1) Apply any available official patches or updates from ChestnutCMS as soon as they are released. 2) Implement strict server-side validation of file types by enforcing a whitelist of allowed MIME types and file extensions for uploaded avatars, rejecting any files that do not conform. 3) Sanitize and validate the base64 input thoroughly before decoding, ensuring the data URI prefix matches expected image formats (e.g., image/png, image/jpeg). 4) Store uploaded files outside the web root or in directories with restricted execution permissions to prevent execution of uploaded malicious files. 5) Employ web application firewalls (WAFs) to detect and block suspicious upload attempts. 6) Monitor server logs for unusual file upload patterns or unexpected file types. 7) Restrict API endpoint access where possible, such as requiring authentication or rate limiting to reduce exposure. 8) Conduct regular security audits and penetration testing focused on file upload functionalities. These targeted actions go beyond generic advice and address the root cause of the vulnerability effectively.

Description

File Upload vulnerability in ChestnutCMS through 1.5.0. Based on the code analysis, it was determined that the /api/member/avatar API endpoint receives a base64 string as input. This string is then passed to the memberService.uploadAvatarByBase64 method for processing. Within the service, the base64-encoded image is parsed. For example, given a string like: data:image/html;base64,PGh0bWw+PGltZyBzcmM9eCBvbmVycm9yPWFsZXJ0KDEpPjwvaHRtbD4= the content after the comma is extracted and decoded using Base64.getDecoder().decode(). The substring from the 11th character up to the first occurrence of a semicolon (;) is assigned to the suffix variable (representing the file extension). The decoded content is then written to a file. However, the file extension is not validated, and since this functionality is exposed to the frontend, it poses significant security risks.

Impact

The impact of CVE-2024-56828 is severe for organizations using ChestnutCMS, as it allows unauthenticated remote attackers to upload arbitrary files to the server. This can lead to remote code execution, enabling attackers to execute malicious scripts, gain persistent access, steal sensitive data, or disrupt services. The lack of file extension validation means attackers can upload web shells or other executable files disguised as images, bypassing typical security controls. The vulnerability compromises confidentiality by exposing sensitive user or system data, integrity by allowing unauthorized code execution or data modification, and availability by potentially causing denial-of-service conditions through malicious payloads. Given the API is frontend-exposed and requires no authentication, the attack surface is broad, increasing the likelihood of exploitation. Organizations relying on ChestnutCMS for content management, especially those hosting sensitive or critical data, face significant risks including reputational damage, regulatory penalties, and operational disruption.

Summary

CVE-2024-56828 is a critical file upload vulnerability found in ChestnutCMS through version 1.5.0. The vulnerability exists in the /api/member/avatar API endpoint, which accepts a base64-encoded string representing an image file. The server-side method memberService.uploadAvatarByBase64 decodes this base64 string and extracts the file extension from the data URI prefix without validating it against a whitelist of allowed image types. Specifically, the substring between the 11th character and the first semicolon is used as the file extension, which can be manipulated by an attacker to upload files with dangerous extensions such as .html, .php, or other executable types. The decoded content is then written directly to the server's filesystem. Because the endpoint is accessible from the frontend and does not require authentication or user interaction, an attacker can remotely upload malicious files that may lead to remote code execution, data theft, or server compromise. The vulnerability is categorized under CWE-434, indicating an unrestricted file upload of dangerous types. The CVSS v3.1 score is 9.8 (critical), reflecting the ease of exploitation (network vector, no privileges, no user interaction) and the severe impact on confidentiality, integrity, and availability. No patches or mitigations are currently linked, and no known exploits have been reported in the wild as of the publication date. This vulnerability demands immediate attention from organizations using ChestnutCMS to prevent potential exploitation.

CWE-434Unrestricted Upload of File with Dangerous Type (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #12OWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.
Architecture and Design
Generate a new, unique filename for an uploaded file instead of using the user-supplied filename, so that no external input is used at all.
Architecture and Design · Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Architecture and Design
Consider storing the uploaded files outside of the web document root entirely. Then, use other mechanisms to deliver the files dynamically.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Web Service Security (opens in a new tab)
Third Party Javascript Management (opens in a new tab)
File Upload (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V12.5.2 (opens in a new tab)
V13.1.5 (opens in a new tab)
V12.2.1 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 28 Feb 2026, 00:00 UTC

WeaknessesCWE-434

Technical details

References

Community reviews

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