State Confusion in GLib via Malformed D-Bus Introspection XML

Executive Summary

CVE-2026-58016 is a security flaw in the GLib library, specifically in the function g_dbus_node_info_new_for_xml() located in gio/gdbusintrospection.c. The vulnerability occurs when the function processes malformed D-Bus introspection XML that contains a <node> element improperly nested inside elements like <method>, <signal>, <property>, or <arg>.

This improper nesting causes the parser's internal state to become inconsistent. When the parser encounters a nested </interface> closing tag, it resets shared data arrays such as data->methods, data->signals, or data->properties to empty. Later, when processing the outer closing tag (e.g., </method>), an unsigned integer underflow occurs because the length variable becomes zero, leading to an out-of-bounds read in memory.

Specifically, the code attempts to access pdata[len - 1], which translates to an invalid memory offset (0xFFFFFFFF * sizeof(gpointer)), causing a large out-of-bounds heap read approximately 8 GB before the buffer. This can result in memory corruption or other security issues.

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can lead to a denial of service (DoS) condition by causing an out-of-bounds read and potential memory corruption in applications using the affected GLib function. An attacker could exploit this flaw by supplying specially crafted malformed D-Bus introspection XML, triggering the parser to crash or behave unpredictably.

Because the vulnerability involves memory corruption, it might also be leveraged for other security issues, although the primary impact is denial of service.

Useful 0 Not Useful 0

Compliance Impact

The vulnerability in GLib causes a denial of service through an out-of-bounds read triggered by malformed D-Bus introspection XML. While it does not directly impact confidentiality or integrity, the resulting denial of service could affect system availability.

Standards and regulations such as GDPR and HIPAA emphasize the importance of maintaining availability, integrity, and confidentiality of systems and data. A denial of service vulnerability could potentially impact compliance by disrupting availability of services that process or store regulated data.

However, there is no direct indication from the provided information that this vulnerability leads to unauthorized data access or disclosure, which are primary concerns under these regulations.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability arises from processing malformed D-Bus introspection XML with improperly nested <node> elements inside <method>, <signal>, <property>, or <arg> elements. Detection would involve monitoring or testing the GLib library's g_dbus_node_info_new_for_xml() function behavior when parsing such XML.

No specific detection commands or network/system scanning methods are provided in the available information.

Useful 0 Not Useful 0

Mitigation Strategies

The provided information does not include explicit mitigation steps or recommended immediate actions.

Useful 0 Not Useful 0