Add restricted execution flags to pdflatex and pandoc commands

Co-authored-by: anchapin <6326294+anchapin@users.noreply.github.com>

Author: google-labs-jules[bot]

.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.
+
+## 2026-08-02 - [Critical] PDF Compilation RCE Vulnerability
+**Vulnerability:** PDF compilation via pdflatex and pandoc lacked restricted execution flags (-no-shell-escape), allowing potential Remote Code Execution if malicious LaTeX is compiled.
+**Learning:** Subprocess calls invoking LaTeX engines must always include -no-shell-escape to sandbox execution and prevent \write18 or shell-escape attacks.
+**Prevention:** Ensure -no-shell-escape is explicitly passed to all LaTeX engine subprocess calls, and handle TimeoutExpired to safely kill stalled processes.

cli/generators/cover_letter_generator.py

@@ -770,13 +770,20 @@ def _compile_pdf(self, output_path: Path, tex_content: str) -> bool:
         pdf_created = False
         try:
             # Use Popen with explicit cleanup to avoid double-free issues
+            # Use -no-shell-escape to prevent RCE during PDF compilation
             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):
@@ -786,12 +793,26 @@ def _compile_pdf(self, output_path: Path, tex_content: str) -> bool:
             else:
                 # Fallback to pandoc
                 try:
+                    # Use -no-shell-escape to prevent RCE during PDF compilation
                     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

@@ -85,13 +85,19 @@ def _compile_pdflatex(
             True if PDF was created successfully
         """
         try:
+            # Use -no-shell-escape to prevent RCE during PDF compilation
             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
@@ -120,13 +126,26 @@ def _compile_pandoc(
             True if PDF was created successfully
         """
         try:
+            # Use -no-shell-escape to prevent RCE during PDF compilation
             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