Unauthenticated unintended actions via Blazor form validation bypass
Published Nov 14, 2023 · Updated Oct 9, 2025
Security feature bypass in Microsoft ASP.NET Core Blazor Server 6.0 through 8.0 RC2 allows remote attackers to trigger unintended form actions. Blazor Server form handling accepts crafted submissions that bypass its intended validation checks, allowing application handlers to process invalid input. Exposure requires an application that uses Blazor Server forms; other ASP.NET Core application types are unaffected, and the resulting action depends on the form handler.
Summary
What happened
Security feature bypass in Microsoft ASP.NET Core Blazor Server 6.0 through 8.0 RC2 allows remote attackers to trigger unintended form actions. Blazor Server form handling accepts crafted submissions that bypass its intended validation checks, allowing application handlers to process invalid input. Exposure requires an application that uses Blazor Server forms; other ASP.NET Core application types are unaffected, and the resulting action depends on the form handler.
The record
- CVE
- CVE-2023-36558
- Published
- Nov 14, 2023
- Updated
- Oct 9, 2025
- Vendor
- Microsoft
- Product
- .NET 6.0
- Classifications
- T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Nov 14, 2023CVE publishedPublication date reported by the CVE source.
- Oct 9, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=6.0.0 <6.0.25
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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