Microsoft .NET up to 6.0.35 DiaSymReader.dll buffer over-read

Summaryinfo

A vulnerability was found in Microsoft .NET up to 6.0.35 and classified as critical. Affected by this issue is some unknown functionality in the library DiaSymReader.dll. The manipulation results in buffer over-read. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is reported as CVE-2025-36855. The attack can be launched remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Microsoft .NET up to 6.0.35. Affected is an unknown code in the library DiaSymReader.dll. The manipulation with an unknown input leads to a buffer over-read vulnerability. CWE is classifying the issue as CWE-126. The product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

A vulnerability ( CVE-2025-21176 https://www.cve.org/CVERecord ) exists in DiaSymReader.dll due to buffer over-read. Per CWE-126: Buffer Over-read https://cwe.mitre.org/data/definitions/126.html , Buffer Over-read is when a product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer. This issue affects EOL ASP.NET 6.0.0 <= 6.0.36 as represented in this CVE, as well as 8.0.0 <= 8.0.11 & <= 9.0.0 as represented in CVE-2025-21176. Additionally, if you've deployed self-contained applications https://docs.microsoft.com/dotnet/core/deploying/#self-contained-deployments-scd  targeting any of the impacted versions, these applications are also vulnerable and must be recompiled and redeployed. NOTE: This CVE affects only End Of Life (EOL) software components. The vendor, Microsoft, has indicated there will be no future updates nor support provided upon inquiry.

The advisory is available at herodevs.com. This vulnerability is traded as CVE-2025-36855 since 04/16/2025. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/08/2025).

Upgrading to version 6.0.36 eliminates this vulnerability.

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Productinfo

Vendor

• Microsoft

Name

• .NET

Version

• 6.0.0
• 6.0.1
• 6.0.2
• 6.0.3
• 6.0.4
• 6.0.5
• 6.0.6
• 6.0.7
• 6.0.8
• 6.0.9
• 6.0.10
• 6.0.11
• 6.0.12
• 6.0.13
• 6.0.14
• 6.0.15
• 6.0.16
• 6.0.17
• 6.0.18
• 6.0.19
• 6.0.20
• 6.0.21
• 6.0.22
• 6.0.23
• 6.0.24
• 6.0.25
• 6.0.26
• 6.0.27
• 6.0.28
• 6.0.29
• 6.0.30
• 6.0.31
• 6.0.32
• 6.0.33
• 6.0.34
• 6.0.35

License

• commercial

Support

• end of life

Website

• Vendor: https://www.microsoft.com/

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