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CVE-2026-21218

CVE-2026-21218 · .NET Spoofing Vulnerability

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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

CVSS 7.5 · High · EPSS 1.0% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • .net 10.0

    Versions
    • ≥ 10.0.0, < 10.0.3: Affected (custom)

    Update to 10.0.3

  • .net 8.0

    Versions
    • ≥ 8.0.0, < 8.0.24: Affected (custom)

    Update to 8.0.24

  • .net 9.0

    Versions
    • ≥ 9.0.0, < 9.0.13: Affected (custom)

    Update to 9.0.13

  • dotnet6 Ubuntu:22.04:LTS

    Versions
    • 6.0.108-0ubuntu1~22.04.1
    • 6.0.109-0ubuntu1~22.04.1
    • 6.0.110-0ubuntu1~22.04.1
    • 6.0.111-0ubuntu1~22.04.1
    • 6.0.113-0ubuntu1~22.04.1
    • 6.0.116-0ubuntu1~22.04.1
    • 6.0.118-0ubuntu1~22.04.1
    • 6.0.119-0ubuntu1~22.04.1
    • 6.0.120-0ubuntu1~22.04.1
    • 6.0.121-0ubuntu1~22.04.1
    • 6.0.122-0ubuntu1~22.04.1
    • 6.0.123-0ubuntu1~22.04.1
    • 6.0.124-0ubuntu1~22.04.1
    • 6.0.125-0ubuntu1~22.04.1
    • 6.0.126-0ubuntu1~22.04.1
    • 6.0.127-0ubuntu1~22.04.1
    • 6.0.128-0ubuntu1~22.04.2
    • 6.0.132-0ubuntu1~22.04.1
    • 6.0.133-0ubuntu1~22.04.1
    • 6.0.135-0ubuntu1~22.04.1
    • 6.0.136-0ubuntu1~22.04.1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dotnet7 Ubuntu:22.04:LTS

    Versions
    • 7.0.105-0ubuntu1~22.04.1
    • 7.0.107-0ubuntu1~22.04.1
    • 7.0.108-0ubuntu1~22.04.1
    • 7.0.109-0ubuntu1~22.04.1
    • 7.0.110-0ubuntu1~22.04.1
    • 7.0.111-0ubuntu1~22.04.1
    • 7.0.112-0ubuntu1~22.04.1
    • 7.0.113-0ubuntu1~22.04.1
    • 7.0.114-0ubuntu1~22.04.1
    • 7.0.115-0ubuntu1~22.04.1
    • 7.0.116-0ubuntu1~22.04.1
    • 7.0.117-0ubuntu1~22.04.1
    • 7.0.117-0ubuntu1~22.04.2
    • 7.0.119-0ubuntu1~22.04.1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • dotnet8 Ubuntu:22.04:LTS

    Versions
    • 8.0.102-8.0.2-0ubuntu1~22.04.1
    • 8.0.103-8.0.3-0ubuntu1~22.04.1
    • 8.0.103-8.0.3-0ubuntu1~22.04.2
    • 8.0.105-8.0.5-0ubuntu1~22.04.1
    • 8.0.107-8.0.7-0ubuntu1~22.04.1
    • 8.0.108-8.0.8-0ubuntu1~22.04.1
    • 8.0.110-8.0.10-0ubuntu1~22.04.1
    • 8.0.111-8.0.11-0ubuntu1~22.04.1
    • 8.0.112-8.0.12-0ubuntu1~22.04.1
    • 8.0.114-8.0.14-0ubuntu1~22.04.1
    • 8.0.115-8.0.15-0ubuntu1~22.04.1
    • 8.0.116-8.0.16-0ubuntu1~22.04.1
    • 8.0.117-8.0.17-0ubuntu1~22.04.1
    • 8.0.118-8.0.18-0ubuntu1~22.04.1
    • 8.0.119-8.0.19-0ubuntu1~22.04.1
    • 8.0.120-8.0.20-0ubuntu1~22.04.1
    • 8.0.121-8.0.21-0ubuntu1~22.04.1
    • 8.0.122-8.0.22-0ubuntu1~22.04.1
    • 8.0.123-8.0.23-0ubuntu1~22.04.1
    Affected ranges
    • ECOSYSTEM: < 8.0.124-8.0.24-0ubuntu1~22.04.1

    Update to 8.0.124-8.0.24-0ubuntu1~22.04.1

  • dotnet10 Ubuntu:24.04:LTS

    Versions
    • 10.0.100-10.0.0-0ubuntu1~24.04.1
    • 10.0.101-10.0.1-0ubuntu1~24.04.2
    Affected ranges
    • ECOSYSTEM: < 10.0.103-10.0.3-0ubuntu1~24.04.1

    Update to 10.0.103-10.0.3-0ubuntu1~24.04.1

  • dotnet8 Ubuntu:24.04:LTS

    Versions
    • 8.0.100-8.0.0~rc1-0ubuntu1
    • 8.0.100-8.0.0~rc2-0ubuntu1
    • 8.0.100-8.0.0~rc2-0ubuntu2
    • 8.0.100-8.0.0-0ubuntu1
    • 8.0.100-8.0.0-0ubuntu2
    • 8.0.101-8.0.1-0ubuntu1
    • 8.0.101-8.0.1-0ubuntu2
    • 8.0.102-8.0.2-0ubuntu1
    • 8.0.103-8.0.3-0ubuntu2
    • 8.0.103-8.0.3-0ubuntu3
    • 8.0.104-8.0.4-0ubuntu1
    • 8.0.105-8.0.5-0ubuntu1~24.04.1
    • 8.0.107-8.0.7-0ubuntu1~24.04.1
    • 8.0.108-8.0.8-0ubuntu1~24.04.1
    • 8.0.108-8.0.8-0ubuntu1~24.04.2
    • 8.0.110-8.0.10-0ubuntu1~24.04.1
    • 8.0.111-8.0.11-0ubuntu1~24.04.1
    • 8.0.112-8.0.12-0ubuntu1~24.04.1
    • 8.0.114-8.0.14-0ubuntu1~24.04.1
    • 8.0.115-8.0.15-0ubuntu1~24.04.1
    • 8.0.116-8.0.16-0ubuntu1~24.04.1
    • 8.0.117-8.0.17-0ubuntu1~24.04.1
    • 8.0.118-8.0.18-0ubuntu1~24.04.1
    • 8.0.119-8.0.19-0ubuntu1~24.04.1
    • 8.0.120-8.0.20-0ubuntu1~24.04.1
    • 8.0.121-8.0.21-0ubuntu1~24.04.1
    • 8.0.122-8.0.22-0ubuntu1~24.04.1
    • 8.0.123-8.0.23-0ubuntu1~24.04.1
    Affected ranges
    • ECOSYSTEM: < 8.0.124-8.0.24-0ubuntu1~24.04.1

    Update to 8.0.124-8.0.24-0ubuntu1~24.04.1

  • dotnet10 Ubuntu:25.10

    Versions
    • 10.0.100-10.0.0~rc1-0ubuntu1
    • 10.0.100-10.0.0~rc2-0ubuntu1~25.10.2
    • 10.0.100-10.0.0-0ubuntu1~25.10.1
    • 10.0.101-10.0.1-0ubuntu1~25.10.2
    Affected ranges
    • ECOSYSTEM: < 10.0.103-10.0.3-0ubuntu1~25.10.1

    Update to 10.0.103-10.0.3-0ubuntu1~25.10.1

  • dotnet8 Ubuntu:25.10

    Versions
    • 8.0.115-8.0.15-0ubuntu1
    • 8.0.116-8.0.16-0ubuntu1
    • 8.0.117-8.0.17-0ubuntu1
    • 8.0.118-8.0.18-0ubuntu1
    • 8.0.119-8.0.19-0ubuntu1
    • 8.0.120-8.0.20-0ubuntu1
    • 8.0.121-8.0.21-0ubuntu1~25.10.1
    • 8.0.122-8.0.22-0ubuntu1~25.10.1
    • 8.0.123-8.0.23-0ubuntu1~25.10.1
    Affected ranges
    • ECOSYSTEM: < 8.0.124-8.0.24-0ubuntu1~25.10.1

    Update to 8.0.124-8.0.24-0ubuntu1~25.10.1

  • dotnet9 Ubuntu:25.10

    Versions
    • 9.0.105-9.0.4-0ubuntu1
    • 9.0.106-9.0.5-0ubuntu1
    • 9.0.107-9.0.6-0ubuntu1
    • 9.0.108-9.0.7-0ubuntu1
    • 9.0.109-9.0.8-0ubuntu1
    • 9.0.110-9.0.9-0ubuntu1
    • 9.0.111-9.0.10-0ubuntu1~25.10.1
    • 9.0.112-9.0.11-0ubuntu1~25.10.1
    • 9.0.113-9.0.12-0ubuntu1~25.10.1
    Affected ranges
    • ECOSYSTEM: < 9.0.114-9.0.13-0ubuntu1~25.10.1

    Update to 9.0.114-9.0.13-0ubuntu1~25.10.1

Original sources

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