External risk intelligence

jpress Command Execution Vulnerability CVE-2021-45807

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2021-45807

JPress is a CMS (Content Management System) application. CMS platforms are commonly deployed as public-facing web applications to serve content, making their administrative and upload interfaces frequently accessible via the internet in standard deployments.

Jpress

4.2.0

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 advisory concerns a critical command execution vulnerability within the jpress Content Management System. The issue allows for arbitrary code to be run on the system without authentication, posing a significant security risk if the affected software is in use. The main concern is confirming relevance and exposure.

Unauthenticated code execution risk.
Critical vulnerability in web content system.
Confirm relevance and potential exposure.

Attack Path

How an attacker could exploit the issue

An attacker could reach a vulnerable component in jpress by exploiting a flaw in the file upload functionality. This could allow an unauthenticated attacker to execute arbitrary commands on the server.

Unauthenticated network access required.
Vulnerable file upload feature.
Arbitrary command execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an unauthenticated attacker to execute arbitrary commands on a server running jpress, potentially impacting the integrity and availability of the application and its underlying system. This could occur when the application's upload functionality is accessible over the network.

Server-side command execution.
Exploits an unauthenticated file upload.
Compromise of server integrity and availability.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in jpress affects application owners and potentially platform or infrastructure teams responsible for web application hosting. The first critical step is to locate all instances of jpress, determine their internet accessibility and business criticality, and identify the specific team or individual accountable for each instance before planning any remediation.

Identify accountable application owners.
Verify internet exposure and business criticality.
Plan remediation based on risk assessment.

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 JPress?

JPress is an open-source Content Management System (CMS) built on Java. It provides users with a platform to design, publish, and manage digital content on websites. Because it functions as a CMS, it includes administrative panels and utility features that allow users to upload files and extend site functionality.

What does CVE-2021-45807 mean?

This vulnerability is a flaw in how the software processes file uploads. It falls under the weakness class of improper input validation, which allows an attacker to bypass security checks. Essentially, the system can be tricked into treating a malicious file as a legitimate command, leading to unauthorized code execution on the server.

How does an attacker trigger this vulnerability?

The vulnerability is triggered by interacting with the administrative file upload component in JPress version 4.2.0. An attacker sends a specific request to this feature to execute commands. Notably, this does not require any administrative login or prior credentials; however, the vulnerability is not triggered by simply viewing standard public content on a site, as it specifically targets the upload-and-install mechanism.

Is my system at risk?

If you are running JPress 4.2.0, you should be concerned, especially if your instance is connected to the internet. According to Halo Surface Signal, CMS platforms are frequently deployed as public-facing web applications. Because this feature is accessible via the network, any instance reachable from the internet has a high likelihood of being exposed to potential remote attacks.

What should I do first if I use JPress?

Start by performing an inventory of your environment to locate every instance of JPress currently running. Once you have a list, verify which instances are accessible over the network and determine the business importance of each. Finally, coordinate with the teams responsible for these applications to prepare for updates or configuration changes.

References

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.