CVE-2026-30821 Vulnerability Analysis & Exploit Details

CVE-2026-30821
Vulnerability Scoring

Analysis In Progress
Analysis In Progress

Attack Complexity Details

  • Attack Complexity:
    Attack Complexity Analysis In Progress
  • Attack Vector:
    Attack Vector Under Analysis
  • Privileges Required: None
    No authentication is required for exploitation.
  • Scope:
    Impact is confined to the initially vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-30821 Details

Status: Received on 07 Mar 2026, 05:16 UTC

Published on: 07 Mar 2026, 05:16 UTC

CVSS Release:

CVE-2026-30821 Vulnerability Summary

CVE-2026-30821: Flowise is a drag & drop user interface to build a customized large language model flow. Prior to version 3.0.13, the /api/v1/attachments/:chatflowId/:chatId endpoint is listed in WHITELIST_URLS, allowing unauthenticated access to the file upload API. While the server validates uploads based on the MIME types defined in chatbotConfig.fullFileUpload.allowedUploadFileTypes, it implicitly trusts the client-provided Content-Type header (file.mimetype) without verifying the file's actual content (magic bytes) or extension (file.originalname). Consequently, an attacker can bypass this restriction by spoofing the Content-Type as a permitted type (e.g., application/pdf) while uploading malicious scripts or arbitrary files. Once uploaded via addArrayFilesToStorage, these files persist in backend storage (S3, GCS, or local disk). This vulnerability serves as a critical entry point that, when chained with other features like static hosting or file retrieval, can lead to Stored XSS, malicious file hosting, or Remote Code Execution (RCE). This issue has been patched in version 3.0.13.

Assessing the Risk of CVE-2026-30821

Access Complexity Graph

The exploitability of CVE-2026-30821 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-30821

No exploitability data is available for CVE-2026-30821.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-30821, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-30821, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-30821 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-30821 does not impact data integrity.
  • Availability: None
    CVE-2026-30821 does not affect system availability.

CVE-2026-30821 References

External References

CWE Common Weakness Enumeration

CWE-434

CAPEC Common Attack Pattern Enumeration and Classification

  • Accessing Functionality Not Properly Constrained by ACLs CAPEC-1 In applications, particularly web applications, access to functionality is mitigated by an authorization framework. This framework maps Access Control Lists (ACLs) to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application, or can run queries for data that they otherwise not supposed to.

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