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Description

Improper handling of missing special element in .NET allows an unauthorized attacker to perform spoofing over a network.

PUBLISHED Reserved 2025-12-11 | Published 2026-02-10 | Updated 2026-02-23 | Assigner microsoft




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C

Problem types

CWE-166: Improper Handling of Missing Special Element

Product status

10.0.0 (custom) before 10.0.3
affected

8.0.0 (custom) before 8.0.24
affected

9.0.0 (custom) before 9.0.13
affected

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21218 (.NET Spoofing Vulnerability) vendor-advisory patch

cve.org (CVE-2026-21218)

nvd.nist.gov (CVE-2026-21218)

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