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Kodbox EUVDEUVD-2026-16072

| CVE-2026-4830 LOW
Unrestricted Upload of File with Dangerous Type (CWE-434)
2026-03-26 VulDB GHSA-264f-3frq-cpxq
2.9
CVSS 4.0 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK

2 techniques across 2 tactics: Command and Control, Persistence

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

While the CVSS 3.1 score of 5.6 indicates moderate severity with a network attack vector (AV:N) and high attack complexity (AC:H), the real-world risk is elevated by several factors: the publicly available proof-of-concept (E:P) significantly increases exploitation probability; the unauthenticated, no-privilege-required attack (PR:N, UI:N) lowers barriers to entry; and vendor non-responsiveness suggests no patch is forthcoming. However, the high attack complexity (AC:H) requirement suggests this is not a trivial one-click exploit. The combination of public POC availability, no vendor remediation, and remote unauthenticated access makes this a moderate-to-high priority despite the moderate CVSS score. The confidentiality, integrity, and availability impacts (C:L, I:L, A:L) are limited by CVSS but could escalate significantly if the uploaded files achieve code execution.

Exploit ScenarioDerived

An attacker discovers a public share link in Kodbox 1.64 and crafts a malicious HTTP request to the Public Share Handler's Add function, bypassing file type validation to upload a PHP webshell. Although the attack requires high complexity (possibly necessitating knowledge of the share token format or parameter structure), once the shell is uploaded to a web-accessible directory, the attacker gains remote code execution by accessing the uploaded file via HTTP. This scenario is plausible given the publicly available proof-of-concept and high likelihood of internet-facing Kodbox installations.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).
No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 26, 2026

An unrestricted file upload vulnerability exists in Kalcaddle Kodbox 1.64 within the Public Share Handler component's userShare.class.php file. This allows unauthenticated remote attackers to upload arbitrary files by manipulating the Add function, potentially leading to remote code execution and system compromise. A publicly available proof-of-concept exists, and the vendor has not responded to early disclosure attempts, increasing the likelihood of active exploitation.

RemediationAI

Immediate action: Upgrade Kalcaddle Kodbox to the latest available version beyond 1.64 if a patch has been released, or contact the Kalcaddle development team for a security update timeline. If patching is not immediately available, implement compensating controls: restrict access to the public share upload functionality via network-level firewall rules or reverse proxy authentication; disable file upload functionality in the Public Share Handler if not essential; implement strict file type validation at the web server level (e.g., Apache/Nginx configuration to block executable file extensions); and monitor upload directories for suspicious file creation. Configure the web server to prevent execution of uploaded files in the target directory via .htaccess (Apache) or nginx configuration. Review access logs for suspicious upload patterns and consider deploying Web Application Firewall (WAF) rules targeting CWE-434 exploitation patterns.

Affected VersionsENISA

kodbox 1.64

Affected Packages

euvd kodbox no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability is rooted in CWE-434 (Unrestricted Upload of File with Dangerous Type), a file upload validation flaw in PHP-based web applications. Specifically, the affected component is app/controller/explorer/userShare.class.php in Kalcaddle Kodbox, which handles public file sharing functionality. The Public Share Handler fails to properly validate or restrict file types during the Add operation, allowing attackers to bypass upload restrictions. This is a classic PHP application vulnerability where insufficient input validation on file uploads allows arbitrary file types to be written to the web-accessible directory, potentially enabling remote code execution if executable files (e.g., .php shells) are uploaded.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 2.9 LOW
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
Low
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

4
Severity Changed
Apr 29, 2026 - 01:11 NVD
MEDIUM LOW
CVSS changed
Apr 29, 2026 - 01:11 NVD
6.3 (MEDIUM) 2.9 (LOW)
PoC Detected
Mar 30, 2026 - 13:26 vuln.today
Public exploit code
CVE Published
Mar 26, 2026 - 00:18 nvd
MEDIUM 6.3

DescriptionCVE.org

A vulnerability was identified in kalcaddle kodbox 1.64. This issue affects the function Add of the file app/controller/explorer/userShare.class.php of the component Public Share Handler. Such manipulation leads to unrestricted upload. The attack can be executed remotely. This attack is characterized by high complexity. The exploitability is assessed as difficult. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.

Executive ViewAI

Why It Matters

Organizations using A vulnerability should be aware of moderate risk from CVE-2026-4830, a unrestricted file upload vulnerability rated CVSS 6.3. This could allow unauthorized file access. Proof-of-concept code is publicly available. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: restrict file access via WAF, implement allowlists.

Threat Intelligence Overview

EPSS Score
0.0%
Top 89% exploitable
Exploit
POC
Public exploit code exists
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity LOW
CISA KEV No
Public POC Yes
EPSS 0.0%
Patch available No
Active threat No
Deciding rule
LOW severity (CVSS 0.1-3.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Defer
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
Low
Technical Impact
Partial

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +14
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.

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