🛡️ Sentinel: [CRITICAL] Fix LaTeX RCE and DoS vulnerabilities

.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.
+
+## 2025-02-21 - [Critical] LaTeX Shell Escape & DoS via Infinite Loops
+**Vulnerability:** LaTeX compilation using `pdflatex` or `pandoc` lacked the `-no-shell-escape` flag. This could allow for arbitrary shell command execution (RCE) if a malicious user or hallucinating AI injected LaTeX commands that leverage `\write18{...}`. Furthermore, the compilation lacked a timeout, meaning a malformed LaTeX document could cause an infinite loop and result in a Denial of Service (DoS) by hanging the worker thread indefinitely.
+**Learning:** Whenever dealing with automated document compilation from untrusted or dynamically generated sources, default settings in tools like `pdflatex` can be extremely dangerous. Subprocesses handling external compilation must have strict boundaries (disabling shell escape) and strict lifespans (timeouts).
+**Prevention:** Always explicitly append `-no-shell-escape` to `pdflatex` commands (and use `--pdf-engine-opt=-no-shell-escape` for `pandoc`). Furthermore, always wrap `subprocess.communicate()` calls in a timeout block, catching `subprocess.TimeoutExpired`, terminating the process with `.kill()`, and re-calling `.communicate()` to prevent zombie processes.

cli/generators/cover_letter_generator.py

@@ -771,12 +771,17 @@ 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()
+                pdf_created = False
             if process.returncode == 0 or output_path.exists():
                 pdf_created = True
         except (subprocess.CalledProcessError, FileNotFoundError):
@@ -787,11 +792,23 @@ 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()
+                        pdf_created = 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()
+                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