CVE-2026-16889 Vulnerability Analysis & Exploit Details

CVE-2026-16889
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-2026-16889 Details

Status: Received on 29 Oct 2026, 02:16 UTC

Published on: 29 Oct 2026, 02:16 UTC

CVSS Release:

CVE-2026-16889 Vulnerability Summary

CVE-2026-16889: In openEQUELLA before 2026.1, the pre-login notice image upload endpoint (PUT /api/preloginnotice/image/{name}) does not validate the type of uploaded files and serves them with a Content-Type derived from the supplied filename. A user holding the EDIT_SYSTEM_SETTINGS permission can upload an HTML file that is then served as text/html from the openEQUELLA origin, resulting in stored cross-site scripting. Unauthenticated exploitation is possible where EDIT_SYSTEM_SETTINGS has been granted to the guest user or everyone.

Assessing the Risk of CVE-2026-16889

Access Complexity Graph

The exploitability of CVE-2026-16889 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-2026-16889

No exploitability data is available for CVE-2026-16889.

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-2026-16889, 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-2026-16889, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-16889 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-16889 does not impact data integrity.
  • Availability: None
    CVE-2026-16889 does not affect system availability.

CVE-2026-16889 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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