# Server-Side Include (SSI) Injection

> Detects user-controlled input reflected in pages processed by SSI, enabling file disclosure and command execution.

- Skill: `zakirkun/server-side-include-ssi-injection` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add zakirkun/server-side-include-ssi-injection`
- Raw SKILL.md: https://api.skillmd.com/api/skills/zakirkun/server-side-include-ssi-injection/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: zakirkun (https://skillmd.com/u/zakirkun)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/zakirkun/server-side-include-ssi-injection

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# Server-Side Include Injection

## Overview
Server-Side Includes (SSI) are directives processed by web servers (Apache, Nginx) before serving files. When user input is reflected in SSI-processed files, attackers can inject directives:
- `<!--#exec cmd="id"-->` — executes arbitrary commands
- `<!--#include file="/etc/passwd"-->` — reads arbitrary files

## Remediation
- Disable SSI processing for user-controlled content
- HTML-encode all user input before including in server-processed pages
- Use Content Security Policy to prevent SSI directive execution