🛡️ Sentinel: [CRITICAL] Fix PDF compilation RCE and DoS vulnerability

.jules/sentinel.md

@@ -7,3 +7,8 @@
 **Vulnerability:** The `CoverLetterGenerator` used a standard Jinja2 environment (intended for HTML/XML or plain text) to render LaTeX templates. This allowed malicious user input (or AI hallucinations) containing LaTeX control characters (e.g., `\input{...}`) to be injected directly into the LaTeX source, leading to potential Local File Inclusion (LFI) or other exploits.
 **Learning:** Jinja2's default `autoescape` is context-aware based on file extensions, but usually only for HTML/XML. It does NOT automatically escape LaTeX special characters. Relying on manual filters (like `| latex_escape`) in templates is error-prone and brittle, as developers might forget to apply them to every variable.
 **Prevention:** Always use a dedicated Jinja2 environment for LaTeX generation that enforces auto-escaping via a `finalize` hook (e.g., `tex_env.finalize = latex_escape`). This ensures *all* variable output is sanitized by default, providing defense-in-depth even if the template author forgets explicit filters.
+
+## 2025-05-28 - [Critical] PDF Compilation RCE and DoS via Missing Subprocess Controls
+**Vulnerability:** `CoverLetterGenerator` and `PDFConverter` used `subprocess.Popen` to call `pdflatex` and `pandoc` without specifying the `-no-shell-escape` flags, opening the possibility for Remote Code Execution (RCE) if a malicious user injects LaTeX shell escape commands. In addition, no `timeout` argument was passed to `process.communicate()`, introducing a Denial of Service (DoS) vulnerability where infinite compilation loops could hang the server.
+**Learning:** Calling command-line tools like `pdflatex` or `pandoc` programmatically requires explicit security boundaries around the subprocess, since their defaults might execute untrusted code or run indefinitely. Even when inputs are escaped properly at the template level, defense-in-depth requires strictly locking down compiler capabilities.
+**Prevention:** Enforce the `-no-shell-escape` flag for `pdflatex` (directly) and `pandoc` (via `--pdf-engine-opt=-no-shell-escape`). Implement subprocess timeouts (e.g., `timeout=30`) with proper explicit process cleanup (catching `subprocess.TimeoutExpired`, executing `process.kill()`, and calling `process.communicate()` a second time) to prevent zombie processes and double-free issues.

cli/generators/cover_letter_generator.py

@@ -771,12 +771,18 @@ def _compile_pdf(self, output_path: Path, tex_content: str) -> bool:
         try:
             # Use Popen with explicit cleanup to avoid double-free issues
             process = subprocess.Popen(
-                ["pdflatex", "-interaction=nonstopmode", tex_path.name],
+                ["pdflatex", "-interaction=nonstopmode", "-no-shell-escape", tex_path.name],
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 cwd=tex_path.parent,
             )
-            stdout, stderr = process.communicate()
+            try:
+                stdout, stderr = process.communicate(timeout=30)
+            except subprocess.TimeoutExpired:
+                process.kill()
+                stdout, stderr = process.communicate()
+                return False
+
             if process.returncode == 0 or output_path.exists():
                 pdf_created = True
         except (subprocess.CalledProcessError, FileNotFoundError):
@@ -787,11 +793,24 @@ def _compile_pdf(self, output_path: Path, tex_content: str) -> bool:
                 # Fallback to pandoc
                 try:
                     process = subprocess.Popen(
-                        ["pandoc", str(tex_path), "-o", str(output_path), "--pdf-engine=xelatex"],
+                        [
+                            "pandoc",
+                            str(tex_path),
+                            "-o",
+                            str(output_path),
+                            "--pdf-engine=xelatex",
+                            "--pdf-engine-opt=-no-shell-escape",
+                        ],
                         stdout=subprocess.PIPE,
                         stderr=subprocess.PIPE,
                     )
-                    stdout, stderr = process.communicate()
+                    try:
+                        stdout, stderr = process.communicate(timeout=30)
+                    except subprocess.TimeoutExpired:
+                        process.kill()
+                        stdout, stderr = process.communicate()
+                        return False
+
                     if process.returncode == 0 or output_path.exists():
                         pdf_created = True
                 except (subprocess.CalledProcessError, FileNotFoundError):

cli/pdf/converter.py

@@ -86,12 +86,17 @@ def _compile_pdflatex(
         """
         try:
             process = subprocess.Popen(
-                ["pdflatex", "-interaction=nonstopmode", tex_path.name],
+                ["pdflatex", "-interaction=nonstopmode", "-no-shell-escape", tex_path.name],
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 cwd=working_dir,
             )
-            stdout, stderr = process.communicate()
+            try:
+                stdout, stderr = process.communicate(timeout=30)
+            except subprocess.TimeoutExpired:
+                process.kill()
+                stdout, stderr = process.communicate()
+                return False
 
             if process.returncode == 0 or output_path.exists():
                 return True
@@ -121,12 +126,24 @@ def _compile_pandoc(
         """
         try:
             process = subprocess.Popen(
-                ["pandoc", str(tex_path), "-o", str(output_path), "--pdf-engine=xelatex"],
+                [
+                    "pandoc",
+                    str(tex_path),
+                    "-o",
+                    str(output_path),
+                    "--pdf-engine=xelatex",
+                    "--pdf-engine-opt=-no-shell-escape",
+                ],
                 stdout=subprocess.PIPE,
                 stderr=subprocess.PIPE,
                 cwd=working_dir,
             )
-            stdout, stderr = process.communicate()
+            try:
+                stdout, stderr = process.communicate(timeout=30)
+            except subprocess.TimeoutExpired:
+                process.kill()
+                stdout, stderr = process.communicate()
+                return False
 
             if process.returncode == 0 or output_path.exists():
                 return True