🛡️ Sentinel: [CRITICAL] Fix Remote Code Execution in PDF Generation

.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.
+
+## 2025-04-30 - [Critical] Remote Code Execution in PDF Generation via LaTeX
+**Vulnerability:** The application converts LaTeX code to PDF using `pdflatex` and `pandoc`. By default, these engines allow execution of arbitrary shell commands using `\write18{}` or similar macros if the `shell-escape` feature is enabled or not explicitly disabled. While some parts of the codebase properly used `-no-shell-escape`, others (`cli/pdf/converter.py` and `cli/generators/cover_letter_generator.py`) did not, leaving the system vulnerable to RCE. Additionally, lack of process timeouts could lead to Denial of Service via infinite compilation loops.
+**Learning:** Security flags and mechanisms (like timeouts and `-no-shell-escape`) must be applied uniformly across *all* instances where an external, potentially dangerous process is invoked. Inconsistent application of security policies creates blind spots.
+**Prevention:** Always enforce the `-no-shell-escape` flag for `pdflatex` and `--pdf-engine-opt=-no-shell-escape` for `pandoc` globally. Ensure all subprocess calls that interact with user-controlled input or generated code include explicit timeouts (e.g., `timeout=30`) and proper error handling.

cli/generators/cover_letter_generator.py

@@ -771,12 +771,19 @@ 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()
+                process.communicate()
+                # Skip to pandoc fallback by raising
+                raise subprocess.CalledProcessError(1, process.args)
+
             if process.returncode == 0 or output_path.exists():
                 pdf_created = True
         except (subprocess.CalledProcessError, FileNotFoundError):
@@ -787,11 +794,25 @@ 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()
+                        process.communicate()
+                        # Pass to failure handler below
+                        raise subprocess.CalledProcessError(1, process.args)
+
                     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()
+                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()
+                process.communicate()
+                return False
 
             if process.returncode == 0 or output_path.exists():
                 return True