External risk intelligence

Symphony XML External Entity Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2020-25912

Symphony is a web content management system. As a web application platform, it is commonly deployed as an internet-facing service to serve public web content, making its XML processing components potentially reachable by internet users.

XML External Entity Injection

Getsymphony Symphony

2.7.10

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

An XML External Entity (XXE) vulnerability has been identified in the Symphony Content Management System. This flaw could allow unauthorized access to information or disrupt service availability. The main concern is confirming whether our Symphony installations are affected and, if so, to what extent.

XML flaw may expose or crash systems.
Confirms relevance and exposure of Symphony systems.
Assess impact and inform relevant stakeholders.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by sending specially crafted XML data to a Symphony CMS website. The vulnerable component, `class.xmlelement.php`, incorrectly processes external entities within this XML, potentially exposing sensitive system information or causing the application to crash.

Accessible via the network.
Triggered by processing malicious XML.
Leads to information disclosure or DoS.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an unauthenticated attacker to disclose sensitive information from the server or cause a denial of service when the affected component processes specially crafted XML input.

Server files and sensitive data.
Via crafted XML input.
Information disclosure or denial of service.

Operational Fix

Recommended remediation, mitigation, and detection steps

This XML External Entity (XXE) vulnerability in Symphony affects components responsible for XML processing, likely managed by platform or application teams. The first practical step is to inventory all Symphony deployments, confirm their internet reachability and business criticality, identify the accountable owner, and then prioritize remediation based on assessed risk.

Platform or application teams own the issue.
Verify Symphony deployment reachability and criticality.
Plan risk-based remediation and vendor coordination.

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 Symphony CMS?

Symphony is a web content management system designed to help developers build and manage dynamic websites. It uses XML for data structure and transformation, acting as a flexible platform that frequently powers public-facing web services.

What does CVE-2020-25912 mean?

This is an XML External Entity (XXE) vulnerability. It occurs when a web application processes XML data without proper security restrictions. Because the software may trust malicious XML input, an attacker can trick the system into revealing internal files or forcing it to stop responding.

How is this vulnerability triggered?

An attacker triggers this by submitting specially crafted XML data to the Symphony application. The issue resides in the way the internal toolkit handles this data. It is important to note that standard, legitimate XML usage by authorized users does not inherently trigger this flaw; the crash or information leak specifically requires the input to contain malicious external entity references.

Why should I care about this Symphony vulnerability?

According to Halo Surface Signal, Symphony is commonly deployed as an internet-facing service, meaning its components are often directly reachable by external users. If your instance is accessible over the internet, an attacker can potentially reach the vulnerable XML processing component without needing prior access or authentication.

What should I do if I use Symphony?

Start by identifying all deployments of Symphony within your organization. Determine which instances are reachable over the internet and establish who owns those systems. Once you have a clear inventory, coordinate with those owners to assess the business risk and prioritize updates or security configurations to mitigate the risk of information disclosure.

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.