External risk intelligence

libxml2 Remote XML Entity Inclusion Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2017-7375

libxml2 is a widely used software library rather than a standalone network service. While it is frequently embedded in internet-facing applications that parse XML, its exposure depends entirely on how the host application utilizes the library. Because it is a foundational component used in diverse internal and external contexts, it is not inherently public-facing by design.

XML External Entity Injection

Xmlsoft Libxml2

2.9.4 and earlier7.08.09.04.4.45.0.25.1.16.06.0.17.1.17.1.22.9.4

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in the widely used libxml2 software library could allow remote attackers to access sensitive content. This could potentially expose data from local files or network resources that are typically protected. The main concern is confirming if and where this library is used in our systems and if the vulnerable configuration is present.

Flaw in software library allows unauthorized content access.
Widely used library; confirm if it's in our environment.
Assess exposure; confirm usage and configuration.

Attack Path

How an attacker could exploit the issue

An attacker can exploit a flaw in the libxml2 library to include external XML content, even when certain default parser settings are disabled. This allows them to access resources from local files or remote servers, potentially revealing sensitive information or expanding the attack surface.

Unauthenticated network access required.
Malicious XML content triggers vulnerability.
Exposure of local or remote content.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to trick a system using libxml2 into retrieving and processing content from external sources, such as local files or network locations. This occurs when specific parser flags are not enabled, potentially exposing sensitive information or leading to unexpected service behavior.

Local files and network content could be exposed.
Maliciously crafted XML could trigger external access.
Unauthorized information disclosure or denial of service.

Operational Fix

Recommended remediation, mitigation, and detection steps

The ownership of this vulnerability likely falls to the application teams that integrate libxml2 into their products, as well as platform or OS providers who bundle it. The immediate first step is to inventory where libxml2 is deployed, assess its exposure to external input, and determine its business criticality before planning remediation.

Identify application owners and their deployments.
Verify external data inputs to libxml2.
Plan coordinated updates or risk mitigation.

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.

Free EASM Trial See How Signal Works

Frequently asked questions

What is libxml2?

libxml2 is a foundational software library used by developers to parse and process XML files. Because it provides core data-handling capabilities, it is embedded within many different products, including various Linux distributions and Android operating systems, to facilitate communication and data structure management.

What does CVE-2017-7375 mean?

This CVE refers to a vulnerability classified as CWE-611, or Improper Restriction of XML External Entity References. It occurs when the library is tricked into processing external data—like local files or remote server content—even when the developer has specifically configured the parser to avoid such behaviors.

How is this vulnerability triggered?

An attacker triggers this by sending a specially crafted XML document to an application using a vulnerable version of libxml2. It is important to note that simply using the library does not automatically trigger the bug; the vulnerability arises specifically when the parser fails to prevent external entity inclusion despite its security settings.

Why should I be concerned about this?

According to Halo Surface Signal, libxml2 is a library rather than a standalone service, so its risk is tied to how specific host applications utilize it. You should care if your systems run software that processes untrusted XML input from the internet, as this could allow unauthorized access to local or remote information.

What should I do to address this?

Begin by inventorying your environment to identify which applications or systems rely on libxml2. Once you have a list of deployments, coordinate with the respective application owners to verify if the library is exposed to external data input and determine the appropriate update or patching path.

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.