Overview
CVE-2026-42167 demonstrates an injection vulnerability in ProFTPD's mod_sql where an attacker supplies a crafted username. When the server logs USER requests with expansions like %U and the SQL backend executes commands, the attacker can trigger remote code execution via SQL injection (CWE-89). This shows how untrusted input can influence backend commands and lead to remote code execution in real systems. In Go (Gin) applications, a similar risk exists when developers concatenate user input into SQL statements, enabling attackers to alter queries or run unintended commands.\n\nIn Go (Gin) apps, an example pattern is building a query string by concatenating a user-provided value like a name into a SQL string, e.g., selecting users where name equals a value supplied by the client. If that input is not parameterized, an attacker can craft input such as a name that closes the string and injects additional SQL. This mirrors CWE-89 exposure: the vulnerability arises from untrusted input influencing SQL execution rather than from the Go language itself.\n\nTo fix this in Go (Gin), never interpolate or concatenate user input into SQL. Use parameterized queries or prepared statements with placeholders appropriate to your database driver, and bind input values safely. Validate and constrain input (length, allowed characters) and consider logging sanitized values rather than raw user input. Also ensure the DB user has least privilege and enable proper error handling to avoid leaking details.\n\nRemediation steps below translate the generic lesson into concrete Go (Gin) practices you can apply in real code.
Code Fix Example
Go (Gin) API Security Remediation
package main
import (
"database/sql"
"log"
"net/http"
"github.com/gin-gonic/gin"
_ "github.com/mattn/go-sqlite3"
)
type User struct {
ID int
Name string
}
func main() {
db, err := sql.Open("sqlite3", ":memory:")
if err != nil {
log.Fatal(err)
}
defer db.Close()
if _, err := db.Exec("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)"); err != nil {
log.Fatal(err)
}
if _, err := db.Exec("INSERT INTO users (name) VALUES ('Alice'), ('Bob')"); err != nil {
log.Fatal(err)
}
r := gin.Default()
// Vulnerable endpoint: demonstrates the insecure pattern (do not reuse in production)
r.GET("/vuln", func(c *gin.Context) {
name := c.Query("name")
// Vulnerable: direct string concatenation of user input into SQL
query := "SELECT id, name FROM users WHERE name = '" + name + "'"
rows, err := db.Query(query)
if err != nil {
c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
return
}
defer rows.Close()
var res []User
for rows.Next() {
var u User
if err := rows.Scan(&u.ID, &u.Name); err == nil {
res = append(res, u)
}
}
c.JSON(http.StatusOK, res)
})
// Fixed endpoint: uses parameterized queries to prevent injection
r.GET("/fix", func(c *gin.Context) {
name := c.Query("name")
rows, err := db.Query("SELECT id, name FROM users WHERE name = ?", name)
if err != nil {
c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
return
}
defer rows.Close()
var res []User
for rows.Next() {
var u User
if err := rows.Scan(&u.ID, &u.Name); err == nil {
res = append(res, u)
}
}
c.JSON(http.StatusOK, res)
})
r.Run(":8080")
}