Overview
The CVE-2026-43937 case shows a dangerous SQL injection vulnerability in YetAnotherForum.NET (YAF.NET) before version 4.0.5. An admin POST handler executes side effects prior to the ResultFilterAttribute redirect to a 302 response, enabling abuse by low-privilege users. The most impactful instance is /Admin/RunSql, where OnPostRunQuery binds Editor from the POST body and passes it directly to IDbAccess.RunSql without caller verification, allowing arbitrary SQL execution. This demonstrates how untrusted input, when concatenated into SQL, can lead to severe data exposure or modification in a real ASP.NET Core app. The underlying CWE mappings are CWE-89 (SQL Injection) and CWE-841 (Access Control/Authorization concerns around insecure method exposure). The fix updates YAF.NET to 4.0.5 and closes the insecure path by enforcing proper authorization and parameterized SQL usage. In ASP.NET Core, this pattern manifests as unvalidated input flowing into database queries via controllers or admin endpoints, bypassing proper security checks.
Affected Versions
≤ 4.0.4 (Prior to 4.0.5)
Code Fix Example
ASP.NET Core API Security Remediation
// Vulnerable pattern (SIMPLIFIED)
[HttpPost]
public IActionResult RunSqlVuln(string editor)
{
// Vulnerable: direct string interpolation of user input into SQL
var sql = $"SELECT * FROM Articles WHERE Title LIKE '%{editor}%'";
using var con = new SqlConnection(_connString);
using var cmd = new SqlCommand(sql, con);
con.Open();
using var reader = cmd.ExecuteReader();
// build and return response (omitted for brevity)
return Ok();
}
// Fixed pattern
[HttpPost]
public IActionResult RunSqlFixed(string editor)
{
// Safe: parameterized query with proper input handling
var sql = "SELECT * FROM Articles WHERE Title LIKE @Editor";
using var con = new SqlConnection(_connString);
using var cmd = new SqlCommand(sql, con);
cmd.Parameters.AddWithValue("@Editor", "%" + editor + "%");
con.Open();
using var reader = cmd.ExecuteReader();
// build and return response (omitted for brevity)
return Ok();
}