GLib Out-of-Bounds Read in g_date_time_get_ymd

Executive Summary

CVE-2026-58011 is a security vulnerability in GLib involving an out-of-bounds read of 2 bytes in the function g_date_time_get_ymd located in glib/gdatetime.c.

This flaw happens when an invalid GDateTime object is created by the g_date_time_add_full function, which does not properly check if the resulting date is within the supported year range (1–9999).

As a result, the GDateTime object can have invalid fields such as negative or zero days. When functions like g_date_time_get_month or g_date_time_get_year are called, the internal function computes a negative array index, causing it to read 2 bytes outside the intended memory bounds.

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Detection Guidance

This vulnerability involves an out-of-bounds read in the GLib library's g_date_time_get_ymd() function when processing invalid GDateTime objects. Detection would typically require checking for the presence of vulnerable GLib versions on your system.

You can detect if your system is affected by verifying the installed GLib version and checking if it includes the fix for CVE-2026-58011.

Suggested commands to check the GLib version on a Linux system include:

• rpm -q glib2
• dpkg -l | grep libglib2.0-0

Additionally, monitoring application logs for crashes or denial of service symptoms related to date/time processing might help identify exploitation attempts.

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Impact Analysis

This vulnerability can corrupt the date output and potentially cause logic errors in applications using GLib's date and time functions.

Such logic errors may lead to a denial of service (DoS) condition, where the affected software could crash or behave unexpectedly.

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Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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Mitigation Strategies

To mitigate this vulnerability, you should update GLib to a version that includes the fix for CVE-2026-58011.

If an immediate update is not possible, consider applying any available patches from your Linux distribution vendor.

As a temporary measure, avoid processing or accepting invalid GDateTime objects that could trigger the out-of-bounds read.

Monitor your systems for unusual behavior or crashes related to date/time functions and restrict untrusted inputs that might exploit this flaw.

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