Overview
The CVE-2026-7820 entry for pgAdmin 4 describes an improper restriction of excessive authentication attempts (CWE-307) where rate-limiting and account lockout were applied only on a single login path (/authenticate/login). An attacker could trigger an account lockout via that route and then bypass the protection by submitting valid credentials to /login, effectively defeating brute-force protections for INTERNAL accounts. The real-world impact was that users’ internal accounts could be targeted with unbounded online password guessing, bypassing lockouts on some endpoints while not on others. This demonstrates a classic Broken Authentication pattern: authentication controls must be applied consistently across all entry points that grant sessions. The remediation requires enforcing the locked state and rate-limiting checks on every authentication path, not only on a subset of endpoints, and ensuring the lockout state persists and is evaluated irrespective of the authentication source. This guidance translates the lesson to Go (Gin) apps by outlining how to enforce a single, centralized authentication policy across all login routes to prevent bypass through alternate endpoints.
In a Go (Gin) context, a similar vulnerability can arise when multiple endpoints exist for signing in and only one uses a comprehensive check of a user’s locked state and recent failed attempts. If /authenticate/login enforces MAX_LOGIN_ATTEMPTS while /login does not consult User.Locked or apply rate-limiting, an attacker can perform online password guessing by alternating between endpoints or exploiting the bypass. The proper remediation is to centralize authentication logic so every path consults the same per-user flags (Active, Locked) and the same password verification, and to store per-user lockout state in durable storage. This reduces risk of bypass and aligns with the lessons from CVE-2026-7820 for pgAdmin 4, ensuring that the same security policy applies regardless of which login endpoint is used.
Affected Versions
pgAdmin 4: before 9.15
Code Fix Example
Go (Gin) API Security Remediation
package main
import (
"fmt"
"log"
"os"
"time"
"github.com/gin-gonic/gin"
"golang.org/x/crypto/bcrypt"
)
type User struct {
Username string
PasswordHash []byte
Active bool
Locked bool
AuthSource string // e.g., INTERNAL, LDAP, OAuth
}
var users map[string]*User
var loginAttempts map[string]int
const MAX_LOGIN_ATTEMPTS = 5
func seedUsers() {
users = make(map[string]*User)
// Create a sample user with a known password: password123
hash, _ := bcrypt.GenerateFromPassword([]byte("password123"), bcrypt.DefaultCost)
users["alice"] = &User{Username: "alice", PasswordHash: hash, Active: true, Locked: false, AuthSource: "INTERNAL"}
}
func getUser(username string) *User {
if u, ok := users[username]; ok {
return u
}
return nil
}
func passwordMatches(u *User, pw string) bool {
if u == nil {
return false
}
err := bcrypt.CompareHashAndPassword(u.PasswordHash, []byte(pw))
return err == nil
}
func createSessionPlaceholder(c *gin.Context, username string) {
// Minimal session emulation for demonstration
c.SetCookie("session_user", username, 3600, "/", "", false, true)
}
// VULNERABLE pattern: LOCKCHECK ONLY ON /authenticate/login
func setupVulnerableRouter() *gin.Engine {
seedUsers()
loginAttempts = make(map[string]int)
r := gin.Default()
// Endpoint 1: enforces lockout on this path only
r.POST("/authenticate/login", func(c *gin.Context) {
type req struct {
Username string `json:\"username\"`
Password string `json:\"password\"`
}
var reqBody req
if err := c.ShouldBindJSON(&reqBody); err != nil {
c.JSON(400, gin.H{"error": "invalid request"})
return
}
u := getUser(reqBody.Username)
if u == nil {
c.JSON(401, gin.H{"error": "invalid credentials"})
return
}
if u.Locked {
c.JSON(403, gin.H{"error": "account locked"})
return
}
if passwordMatches(u, reqBody.Password) {
loginAttempts[reqBody.Username] = 0
createSessionPlaceholder(c, u.Username)
c.JSON(200, gin.H{"message": "authenticated (vuln)"})
return
}
loginAttempts[reqBody.Username]++
if loginAttempts[reqBody.Username] >= MAX_LOGIN_ATTEMPTS && u.AuthSource == "INTERNAL" {
u.Locked = true
}
c.JSON(401, gin.H{"error": "invalid credentials"})
})
// Endpoint 2: vulnerable path that does not consult locked state
r.POST("/login", func(c *gin.Context) {
type req struct {
Username string `json:\"username\"`
Password string `json:\"password\"`
}
var reqBody req
if err := c.ShouldBindJSON(&reqBody); err != nil {
c.JSON(400, gin.H{"error": "invalid request"})
return
}
u := getUser(reqBody.Username)
if u == nil {
c.JSON(401, gin.H{"error": "invalid credentials"})
return
}
// Vulnerability: does not check u.Locked (bypass) and does not enforce cross-endpoint rate-limiting
if passwordMatches(u, reqBody.Password) {
createSessionPlaceholder(c, u.Username)
c.JSON(200, gin.H{"message": "authenticated (vuln)"})
return
}
c.JSON(401, gin.H{"error": "invalid credentials"})
})
return r
}
// FIXED pattern: centralize checks so both endpoints enforce lockout and act consistently
func setupFixedRouter() *gin.Engine {
seedUsers()
loginAttempts = make(map[string]int)
r := gin.Default()
r.POST("/authenticate/login", func(c *gin.Context) {
type req struct {
Username string `json:\"username\"`
Password string `json:\"password\"`
}
var reqBody req
if err := c.ShouldBindJSON(&reqBody); err != nil {
c.JSON(400, gin.H{"error": "invalid request"})
return
}
u := getUser(reqBody.Username)
if u == nil {
c.JSON(401, gin.H{"error": "invalid credentials"})
return
}
if !u.Active {
c.JSON(403, gin.H{"error": "inactive user"})
return
}
if u.Locked {
c.JSON(403, gin.H{"error": "account locked"})
return
}
if passwordMatches(u, reqBody.Password) {
loginAttempts[reqBody.Username] = 0
createSessionPlaceholder(c, u.Username)
c.JSON(200, gin.H{"message": "authenticated (fixed)"})
return
}
loginAttempts[reqBody.Username]++
if loginAttempts[reqBody.Username] >= MAX_LOGIN_ATTEMPTS && u.AuthSource == "INTERNAL" {
u.Locked = true
}
c.JSON(401, gin.H{"error": "invalid credentials"})
})
r.POST("/login", func(c *gin.Context) {
type req struct {
Username string `json:\"username\"`
Password string `json:\"password\"`
}
var reqBody req
if err := c.ShouldBindJSON(&reqBody); err != nil {
c.JSON(400, gin.H{"error": "invalid request"})
return
}
u := getUser(reqBody.Username)
if u == nil {
c.JSON(401, gin.H{"error": "invalid credentials"})
return
}
// Fixed: enforce identical checks as /authenticate/login
if !u.Active {
c.JSON(403, gin.H{"error": "inactive user"})
return
}
if u.Locked {
c.JSON(403, gin.H{"error": "account locked"})
return
}
if passwordMatches(u, reqBody.Password) {
loginAttempts[reqBody.Username] = 0
createSessionPlaceholder(c, u.Username)
c.JSON(200, gin.H{"message": "authenticated (fixed)"})
return
}
c.JSON(401, gin.H{"error": "invalid credentials"})
})
return r
}
func main() {
mode := os.Getenv("MODE")
if mode == "FIX" {
r := setupFixedRouter()
if err := r.Run(":8080"); err != nil {
log.Fatal(err)
}
return
}
// Default to vulnerable demonstration
r := setupVulnerableRouter()
if err := r.Run(":8080"); err != nil {
log.Fatal(err)
}
}