Microsoft ASP.NET up to 5.1 infinite loop

Summaryinfo

A vulnerability was found in Microsoft ASP.NET. It has been classified as problematic. This issue affects some unknown processing. This manipulation causes infinite loop. This vulnerability is registered as CVE-2026-42899. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in Microsoft ASP.NET and classified as problematic. Affected by this vulnerability is an unknown code block. The manipulation with an unknown input leads to a infinite loop vulnerability. The CWE definition for the vulnerability is CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. As an impact it is known to affect availability. The summary by CVE is:

Loop with unreachable exit condition ('infinite loop') in ASP.NET Core allows an unauthorized attacker to deny service over a network.

The weakness was published 05/12/2026 as confirmed security update guide (Website). It is possible to read the advisory at msrc.microsoft.com. This vulnerability is known as CVE-2026-42899. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/03/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 314680 (Security Update for Microsoft .NET Core SDK (May 2026)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 8.0.27 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (314680). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• Microsoft

Name

• ASP.NET

Version

• 1
• 1.0
• 1.0.0
• 1.0.0-RC2
• 1.1
• 1.1.1
• 2
• 2.0
• 2.1
• 2.2
• 3
• 3.0
• 3.1
• 3.5
• 4
• 5
• 5-RC1
• 5.1

License

• commercial

Website

• Vendor: https://www.microsoft.com/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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