Advisory Details

April 15th, 2026

Microsoft Qlib fit Deserialization of Untrusted Data Remote Code Execution Vulnerability

ZDI-26-274
ZDI-CAN-27211

CVE ID
CVSS SCORE 7.8, AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Qlib
VULNERABILITY DETAILS

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Qlib. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the fit function. The issue results from the lack of proper validation of user-supplied data, which can result in deserialization of untrusted data. An attacker can leverage this vulnerability to execute code in the context of root.
ADDITIONAL DETAILS

Fixed on May 31, 2025 https://msrc.microsoft.com/update-guide/acknowledgement/online
DISCLOSURE TIMELINE
  • 2025-05-22 - Vulnerability reported to vendor
  • 2026-04-15 - Coordinated public release of advisory
  • 2026-04-15 - Advisory Updated
CREDIT Peter Girnus (@gothburz) of Trend Zero Day Initiative
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