Overview
CVE-2026-5665 describes a SQL injection vulnerability in code-projects Online FIR System 1.0 where the login flow manipulated user-provided credentials to alter SQL queries. The vulnerability (CWE-89, with related CWE-74 context) is exploitable remotely and has had public disclosures, enabling attackers to read or modify data without authorization. Although this CVE targets a PHP component (/Login/checklogin.php) rather than Go, the root flaw-unsafely combining user input into SQL-maps directly to similar injection risks in Go (Gin) applications when queries are constructed via string interpolation rather than parameter binding. This real-world exposure underscores the urgency of adopting safe query practices in Go services to prevent authentication bypass and data leakage. The guidance here ties the CVE’s risk to Go (Gin) patterns to help developers preempt similar attacks in their Go codebases.
In Go (Gin) applications, this vulnerability manifests when developers construct SQL statements by concatenating or interpolating user-supplied input into queries. If an attacker provides crafted values for email or password, the resulting SQL can change program logic, bypass authentication, or access unintended data. While CVE-2026-5665 focuses on a PHP login path, the injection principle remains highly relevant: failing to bind parameters securely enables remote exploitation of login logic in Go services as well. This guide demonstrates how to translate the same mitigation concepts into idiomatic Go (Gin) code using parameterized queries and secure authentication practices.
Remediation in real Go (Gin) code requires adopting parameter binding for all dynamic SQL, hashing and verifying passwords, least-privilege DB access, input validation, and robust monitoring. Start by replacing string-interpolated queries with parameterized forms, use prepared statements where appropriate, and prefer an ORM or the database/sql API’s placeholders ($1, $2 or ?) appropriate to your driver. Validate inputs (e.g., proper email format), store password hashes with bcrypt/argon2, and never compare plaintext passwords. Finally, ensure the application enforces least privilege, exerts rate limiting on login attempts, and logs anomalies for alerting and future hardening.
Code Fix Example
Go (Gin) API Security Remediation
package main
import (
"database/sql"
"fmt"
"log"
"net/http"
"github.com/gin-gonic/gin"
_ "github.com/lib/pq"
)
var db *sql.DB
func initDB() {
var err error
// Example Postgres connection string; replace with real credentials in your environment
connStr := "postgres://user:pass@localhost/dbname?sslmode=disable"
db, err = sql.Open("postgres", connStr)
if err != nil {
log.Fatal(err)
}
if err = db.Ping(); err != nil {
log.Fatal(err)
}
}
func main() {
initDB()
r := gin.Default()
// Vulnerable endpoint (for demonstration only): uses string concatenation and is insecure
r.POST("/login", loginVulnerable)
// Fixed endpoint: uses parameterized queries to prevent injection
r.POST("/login-fixed", loginFixed)
_ = r.Run(":8080")
}
// Vulnerable version: susceptible to SQL injection via email/password inputs
func loginVulnerable(c *gin.Context) {
email := c.PostForm("email")
password := c.PostForm("password")
// Vulnerable: direct string interpolation
query := fmt.Sprintf("SELECT id FROM users WHERE email = '%s' AND password = '%s'", email, password)
var id int
err := db.QueryRow(query).Scan(&id)
if err != nil {
c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
return
}
c.JSON(http.StatusOK, gin.H{"id": id})
}
// Fixed version: uses parameterized queries to prevent injection
func loginFixed(c *gin.Context) {
email := c.PostForm("email")
password := c.PostForm("password")
var id int
// Use parameterized placeholder ($1, $2) for PostgreSQL driver
if err := db.QueryRow("SELECT id FROM users WHERE email = $1 AND password = $2", email, password).Scan(&id); err != nil {
c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
return
}
c.JSON(http.StatusOK, gin.H{"id": id})
}