Overview
CVE-2025-10908 describes a Broken Object Level Authorization (CWE-863) flaw in Go (Gin) authentication flows where the system does not validate the user account state during authentication. Specifically, locked user accounts could still be authenticated via Magic Link or Pass Key mechanisms, bypassing the account lock and granting access to data and functionality that should be restricted. In real-world apps, this can mean unauthorized viewing or manipulation of sensitive user data, bypassing security controls intended to prevent access to locked accounts. The weakness arises when an authentication step trusts a token’s identity (or a derived user), but neglects to enforce the current account state before issuing a session or access token. This undermines the purpose of account locking and can enable credential-stuffing, account takeover of locked accounts, or inadvertent data exposure even when an account is marked as locked.
In practice, this manifests in Go (Gin) services where passwordless flows (magic links or passkeys) rely on token payloads to identify the user, then immediately grant access without checking whether the account is currently locked. An attacker who can obtain or intercept a magic link or passkey token associated with a locked account-or trigger a login flow that uses a locked account’s identity-can authenticate successfully. The fix is to ensure that, at the point where the application decides whether to authorize a session, the current account state is checked against the database and the request is rejected if the account is locked. This check must be consistent across all authentication endpoints (password-based and passwordless) and should be supported by tests that verify locked accounts cannot obtain sessions via any flow.
The remediation pattern is to fetch the user state by the identity asserted by the token (or session) and then enforce that state before granting access. A robust fix includes: validating the account state after resolving the user from any token, returning a forbidden status for locked accounts, and ensuring that all authentication paths (including magic link and passkey flows) perform this check. Consider centralizing this in a helper or middleware to guarantee uniform behavior and to simplify testing and auditing. Finally, implement unit/integration tests to cover locked accounts across login paths and add logging for blocked attempts and lock state events.
Code Fix Example
Go (Gin) API Security Remediation
package main
import (
"errors"
"net/http"
"strings"
"github.com/gin-gonic/gin"
)
type User struct {
ID string
Email string
Locked bool
}
var users = map[string]User{
`1`: {ID: `1`, Email: `[email protected]`, Locked: true},
`2`: {ID: `2`, Email: `[email protected]`, Locked: false},
}
func getUserByID(id string) (*User, error) {
if u, ok := users[id]; ok {
return &u, nil
}
return nil, errors.New(`not found`)
}
func verifyMagicToken(token string) (string, error) {
// Simple token format: `magic:<user_id>`
parts := strings.Split(token, `:`)
if len(parts) != 2 || parts[0] != `magic` {
return ``, errors.New(`invalid token`)
}
return parts[1], nil
}
func main() {
r := gin.Default()
r.POST(`/login/vulnerable`, loginVulnerable)
r.POST(`/login/fixed`, loginFixed)
r.Run(`:8080`)
}
func loginVulnerable(c *gin.Context) {
token := c.PostForm(`token`)
userID, err := verifyMagicToken(token)
if err != nil {
c.JSON(http.StatusBadRequest, gin.H{`error`: `invalid token`})
return
}
user, err := getUserByID(userID)
if err != nil {
c.JSON(http.StatusUnauthorized, gin.H{`error`: `unauthorized`})
return
}
// Vulnerable: does not enforce account lock state
c.JSON(http.StatusOK, gin.H{`message`: `access granted (vulnerable)`, `email`: user.Email})
}
func loginFixed(c *gin.Context) {
token := c.PostForm(`token`)
userID, err := verifyMagicToken(token)
if err != nil {
c.JSON(http.StatusBadRequest, gin.H{`error`: `invalid token`})
return
}
user, err := getUserByID(userID)
if err != nil {
c.JSON(http.StatusUnauthorized, gin.H{`error`: `unauthorized`})
return
}
// Mitigation: enforce account lock state
if user.Locked {
c.JSON(http.StatusForbidden, gin.H{`error`: `account locked`})
return
}
c.JSON(http.StatusOK, gin.H{`message`: `access granted (fixed)`, `email`: user.Email})
}