Overview
CVE-2026-24620 describes a Stored XSS vulnerability in PluginOps Landing Page Builder's page-builder-add feature, where input generated on a web page could be improperly neutralized and stored, then rendered back to other users. Attackers could inject script payloads into stored content, which would execute when other users (including site admins) viewed the affected landing pages. This vulnerability stems from insufficient input handling and rendering paths that do not properly escape or sanitize user-provided HTML, enabling cross-site scripts to persist in the database and execute in trusted contexts. In Go (Gin) terms, similar patterns can arise when endpoints that modify or fetch page content do not enforce object-level authorization and also render user-supplied HTML without proper escaping or sanitization. The CVE notes the affected range as Landing Page Builder: from n/a through <= 1.5.3.3 and lists CWE-79 (XSS). This guide shows how such issues can be exploited and how to remediate in real Go (Gin) code by combining strict per-object authorization with safe content rendering and sanitization.
Affected Versions
N/A to <= 1.5.3.3
Code Fix Example
Go (Gin) API Security Remediation
package main
import (
htmlTpl "html/template"
"net/http"
"strconv"
"github.com/gin-gonic/gin"
)
type VulnerablePage struct {
ID int
Title string
Content htmlTpl.HTML // unescaped HTML content (vulnerable path)
OwnerID int
}
type FixedPage struct {
ID int
Title string
Content string // escaped by template rendering
OwnerID int
}
var vPages = map[int]*VulnerablePage{}
var fPages = map[int]*FixedPage{}
func getUserID(c *gin.Context) int {
s := c.GetHeader("X-User-ID")
id, _ := strconv.Atoi(s)
return id
}
func main() {
r := gin.Default()
// Seed sample pages
vPages[1] = &VulnerablePage{ID: 1, Title: "Landing Page", Content: htmlTpl.HTML("<p>Initial</p>"), OwnerID: 2}
fPages[1] = &FixedPage{ID: 1, Title: "Landing Page", Content: "<p>Initial</p>", OwnerID: 2}
// Vulnerable: no per-object authorization on content updates; content is stored as unescaped HTML
r.POST("/vuln/pages/:id/content", func(c *gin.Context) {
id, _ := strconv.Atoi(c.Param("id"))
page, ok := vPages[id]
if !ok {
c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
return
}
user := getUserID(c)
if user == 0 {
c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
return
}
var req struct{ Content string `json:"content"` }
if err := c.ShouldBindJSON(&req); err != nil {
c.JSON(http.StatusBadRequest, gin.H{"error": "invalid payload"})
return
}
// Vulnerable: no ownership check for the page being updated
page.Content = htmlTpl.HTML(string(page.Content) + req.Content)
c.JSON(http.StatusOK, gin.H{"content": string(page.Content)})
})
// Vulnerable view: renders Content without escaping (due to html/template HTML type)
r.GET("/vuln/pages/:id/view", func(c *gin.Context) {
id, _ := strconv.Atoi(c.Param("id"))
page, ok := vPages[id]
if !ok {
c.String(http.StatusNotFound, "not found")
return
}
tmpl := htmlTpl.Must(htmlTpl.New("page").Parse("<h1>{{.Title}}</h1><div>{{.Content}}</div>"))
tmpl.Execute(c.Writer, page)
})
// Fixed: enforce per-object authorization and escape/sanitize content on render
r.POST("/fix/pages/:id/content", func(c *gin.Context) {
id, _ := strconv.Atoi(c.Param("id"))
page, ok := fPages[id]
if !ok {
c.JSON(http.StatusNotFound, gin.H{"error": "not found"})
return
}
user := getUserID(c)
if user == 0 {
c.JSON(http.StatusUnauthorized, gin.H{"error": "unauthorized"})
return
}
if user != page.OwnerID {
c.JSON(http.StatusForbidden, gin.H{"error": "forbidden"})
return
}
var req struct{ Content string `json:"content"` }
if err := c.ShouldBindJSON(&req); err != nil {
c.JSON(http.StatusBadRequest, gin.H{"error": "invalid payload"})
return
}
// Fixed: content is stored as plain string; rendering escapes HTML by default
page.Content += req.Content
c.JSON(http.StatusOK, gin.H{"content": page.Content})
})
r.GET("/fix/pages/:id/view", func(c *gin.Context) {
id, _ := strconv.Atoi(c.Param("id"))
page, ok := fPages[id]
if !ok {
c.String(http.StatusNotFound, "not found")
return
}
tmpl := htmlTpl.Must(htmlTpl.New("page").Parse("<h1>{{.Title}}</h1><div>{{.Content}}</div>"))
tmpl.Execute(c.Writer, page)
})
r.Run(":8080")
}