🛡️ CVE-2025-55248 — .net

🟡 CVSS 5.0 — Medium ✅ No Known Exploit CWE-326 NVD
5.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Microsoft Security Advisory CVE-2025-55248: .NET Information Disclosure Vulnerability

# Microsoft Security Advisory CVE-2025-55248 | .NET Information Disclosure Vulnerability

<a name="executive-summary"></a>Executive summary

Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 8.0 and .NET 9.0. This advisory also provides guidance on what developers can do to update their applications to remove this vulnerability.

A MITM (man in the middle) attacker may prevent use of TLS between client and SMTP server, forcing client to send data over unencrypted connection.

Announcement

Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/372

<a name="mitigation-factors"></a>Mitigation factors

Microsoft has not identified any mitigating factors for this vulnerability.

<a name="affected-software"></a>Affected software

  • Any .NET 8.0 application running on .NET 8.0.20 or earlier.
  • Any .NET 9.0 application running on .NET 9.0.9 or earlier.

<a name="affected-packages"></a>Affected Packages

The vulnerability affects any Microsoft .NET project if it uses any of affected packages versions listed below

<a name=".NET 9"></a>.NET 9

Package name | Affected version | Patched version

------------ | ---------------- | -------------------------

[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 9.0.0, < =9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.win-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x64) | >= 9.0.0, <= 9.0.9 | 9.0.10

[Microsoft.NetCore.App.Runtime.win-x86](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-x86) | >= 9.0.0, <= 9.0.9 | 9.0.10

<a name=".NET 8"></a>.NET 8

Package name | Affected version | Patched version

------------ | ---------------- | -------------------------

[Microsoft.NetCore.App.Runtime.linux-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.linux-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-arm64) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.linux-musl-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.linux-musl-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-arm64) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.linux-musl-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-musl-x64) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.linux-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.linux-x64) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.osx-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-arm64) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.osx-x64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.osx-x64) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.win-arm](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.App.Runtime.win-arm64](https://www.nuget.org/packages/Microsoft.NetCore.App.Runtime.win-arm64) | >= 8.0.0, <= 8.0.20 | 8.0.21

[Microsoft.NetCore.A

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs low-level privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

Weakness class

CVE-2025-55248 is classified as CWE-326: Inadequate Encryption Strength. Encryption is applied, but with a key length or scheme too weak to resist a realistic attacker.

Affected software

CVE-2025-55248 is recorded against 17 packages.

  • .net (from 9.0.0 up to 9.0.10)
  • .net-framework
  • dotnet
  • dotnet-sdk
  • microsoft.netcore.app.runtime.linux-arm (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.linux-arm64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.linux-musl-arm (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.linux-musl-arm64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.linux-musl-x64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.linux-x64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.osx-arm64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.osx-x64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.win-arm (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.win-arm64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.win-x64 (from 8.0.0 up to 8.0.21)
  • microsoft.netcore.app.runtime.win-x86 (from 8.0.0 up to 8.0.21)
  • visual-studio-2022 (from 17.14.0 up to 17.14.17)

Timeline and source

Published on 14 October 2025 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

msrc.microsoft.com

CVE-2025-55248 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 5.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N
CWE CWE-326
Public Exploit ✅ No
Source NVD
Published 2025-10-14
Updated 2026-08-12
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
.net 9.0.0 9.0.10
.net-framework — —
dotnet — —
dotnet-sdk — —
microsoft.netcore.app.runtime.linux-arm 8.0.0 8.0.21
microsoft.netcore.app.runtime.linux-arm64 8.0.0 8.0.21
microsoft.netcore.app.runtime.linux-musl-arm 8.0.0 8.0.21
microsoft.netcore.app.runtime.linux-musl-arm64 8.0.0 8.0.21
microsoft.netcore.app.runtime.linux-musl-x64 8.0.0 8.0.21
microsoft.netcore.app.runtime.linux-x64 8.0.0 8.0.21
microsoft.netcore.app.runtime.osx-arm64 8.0.0 8.0.21
microsoft.netcore.app.runtime.osx-x64 8.0.0 8.0.21
microsoft.netcore.app.runtime.win-arm 8.0.0 8.0.21
microsoft.netcore.app.runtime.win-arm64 8.0.0 8.0.21
microsoft.netcore.app.runtime.win-x64 8.0.0 8.0.21
microsoft.netcore.app.runtime.win-x86 8.0.0 8.0.21
visual-studio-2022 17.14.0 17.14.17

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