Overview
Stored cross-site scripting via logs is a real-world risk that can affect Go applications using Gin. The CVE-2026-34560 example from the CodeIgniter 4-based CI4MS project shows how user-controlled input rendered unsafely in a logs interface can become a blind XSS vector: payloads stored in logs are not properly encoded, and an administrator viewing the logs page triggers script execution later. While that CVE concerns PHP, the vulnerability class transfers directly to Go (Gin) apps whenever untrusted data is concatenated into HTML or rendered without proper escaping. In practice, an attacker could inject HTML or script content into logs or admin UI fields and have it execute in the admin’s browser when the page is opened. The mitigation is to enforce strict output encoding and template-based rendering for all user-controlled content, and to treat logs as untrusted data that must be escaped before display. This guidance translates the risk into concrete Go (Gin) patterns and fixes. The CVE reference is included to contextualize the risk and the need for proper encoding in logs and admin interfaces.
Code Fix Example
Go (Gin) API Security Remediation
VULNERABLE:
package main
import (
"bufio"
"net/http"
"os"
"github.com/gin-gonic/gin"
)
func readLogs() []string {
f, err := os.Open("logs.txt")
if err != nil {
return []string{}
}
defer f.Close()
var lines []string
scanner := bufio.NewScanner(f)
for scanner.Scan() {
lines = append(lines, scanner.Text())
}
return lines
}
func vulnerableLogs(c *gin.Context) {
lines := readLogs()
html := "<html><body>Logs:<br/>"
for _, l := range lines {
html += l + "<br/>" // vulnerability: unescaped user input rendered as HTML
}
html += "</body></html>"
c.String(http.StatusOK, html)
}
func main() {
r := gin.Default()
r.GET("/logs", vulnerableLogs)
r.Run(":8080")
}
FIX:
package main
import (
"bufio"
"net/http"
"os"
"github.com/gin-gonic/gin"
"html/template"
)
func readLogs() []string {
f, err := os.Open("logs.txt")
if err != nil {
return []string{}
}
defer f.Close()
var lines []string
scanner := bufio.NewScanner(f)
for scanner.Scan() {
lines = append(lines, scanner.Text())
}
return lines
}
func safeLogs(c *gin.Context) {
lines := readLogs()
// Template escapes HTML by default, preventing stored XSS in logs rendering
const tpl = `<html><body>Logs:<br/>{{range .}}<div>{{.}}</div>{{end}}</body></html>`
t := template.Must(template.New("logs").Parse(tpl))
c.Status(http.StatusOK)
t.Execute(c.Writer, lines)
}
func main() {
r := gin.Default()
r.GET("/logs", safeLogs)
r.Run(":8080")
}