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Microsoft Security Response CenterCVE-2026-86138

In libxml2 before 2.15.4, xmlDictAddQString in dict.c has an integer overflow and resultant heap-based buffer overflow.

MediumVendor CVSS 6.9 / 10 1 CVE Published Sep 6, 2026 at 4:36 AM UTC

Summary

Mariner

Products covered

  • azl3 libxml2 2.11.5-10 on Azure Linux 3.0

  • azl3 libxml2 2.11.5-11 on Azure Linux 3.0

Remediation

See the Microsoft Security Update Guide for the update that applies to your product.

Vendor-listed fixes

  • 2.11.5-11

CVEs in this advisory 1

Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

    • Added affected products: azl3 libxml2 2.11.5-11 on Azure Linux 3.0.
    • Added fixed versions: 2.11.5-11.

Updates

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

  3. Updated by Microsoft Security Response Center

    The vendor changed the advisory after it was first published.

  4. Confirmed at the source

    Our collector saw this advisory during a later source check.