External risk intelligence

Drupal Flag Attendance Field Object Injection Vulnerability

CVE advisorySeverity: HIGH (CVSS 8.1)

CVE-2026-55809

The vulnerability affects a Drupal module, which is typically deployed as part of public-facing web applications. Drupal sites are commonly exposed to the internet to serve content or interact with users, making the underlying module code reachable via standard web requests.

Flag Attendance Field Project Flag Attendance Field

before 1.2

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability concerns a security flaw in a specific Drupal module that allows for unauthorized modification of data, potentially enabling malicious actors to inject or alter objects within the system. While the exact business impact is still under analysis, the critical severity suggests a potential for significant compromise if exploited. The main concern is confirming if your organization utilizes this particular Drupal module and what data it manages.

Allows unauthorized data modification.
Critical severity warrants attention.
Confirm relevance and exposure.

Attack Path

How an attacker could exploit the issue

An attacker can remotely exploit this vulnerability by sending a specially crafted request to a Drupal site that has the Flag attendance field module installed. This request targets the module's improper handling of dynamically determined object attributes, leading to object injection and potentially allowing the attacker to execute arbitrary code.

Accessible via the network.
Triggers through improper input handling.
Allows arbitrary code execution.

Live Threat

Current exploitation, exposure, and threat context

A vulnerability in the Flag attendance field for Drupal could allow an attacker to inject malicious objects, potentially leading to the compromise of the system. This could occur when the attendance field is used in a way that allows for improperly controlled modification of dynamically determined object attributes.

System data could be affected.
Injection may occur through network requests.
Object injection could lead to system compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the Drupal Flag attendance field requires coordination between application owners responsible for the Drupal instance and potentially platform or infrastructure teams managing the web hosting environment. The first practical step is to confirm if the affected Drupal module is deployed, assess its exposure to external or internal networks, and identify the specific application owner or team accountable for its maintenance and security. Remediation planning should be risk-based, considering the criticality of the affected applications and the potential impact of the vulnerability.

Application owners must prioritize this issue.
Verify deployment of the Flag attendance field module.
Plan remediation based on risk and impact.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the Flag attendance field for Drupal?

It is a specialized plugin module for Drupal, a popular content management framework. Developers use Drupal to build dynamic websites and complex web applications. This specific module adds custom fields to track attendance or event participation data within a Drupal site's existing content structure.

What does CVE-2026-55809 mean?

This vulnerability is classified as Improperly Controlled Modification of Dynamically-Determined Object Attributes (CWE-915). In plain terms, the module fails to properly validate incoming data, which allows an attacker to manipulate internal system objects. This type of weakness can lead to 'Object Injection,' where the system inadvertently processes malicious data as legitimate instructions, potentially giving an attacker control over the application.

How is this vulnerability triggered?

An attacker triggers this flaw by sending a specially crafted network request to a site running the affected module. The system processes this input incorrectly, leading to the object injection. It is important to note that the vulnerability exists within the module's attribute handling logic; simply viewing a page or authenticating as a standard user does not prevent the issue, as the flaw resides in how the software processes incoming data structures.

Is my site at risk if it runs this module?

According to Halo Surface Signal, this module is typically part of Drupal sites that are publicly accessible to interact with users. Because Drupal sites are frequently deployed as internet-facing web applications to serve content, this module is often reachable via standard network requests. If your site is reachable from the internet, it should be considered a potential target for remote exploitation.

How should I respond to this threat?

Your first step is to inventory your Drupal environments to identify where the Flag attendance field module is installed. Once identified, consult with your application owners to determine the specific role of the module and its exposure. Prioritize this based on the application's criticality and prepare to apply updates or disable the module if it is not essential for business operations while you await vendor-supplied patches.

References

www.drupal.org/sa-contrib-2026-049

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.