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

[anchapin]

🚨 Severity: CRITICAL
💡 Vulnerability: Missing -no-shell-escape and timeout in PDF compilation
🎯 Impact: Remote Code Execution (RCE) via LaTeX injections and Denial of Service (DoS) via compilation hangs
🔧 Fix: Added -no-shell-escape, --pdf-engine-opt=-no-shell-escape, and timeout=30 to pdflatex and pandoc subprocess calls. Properly handle subprocess.TimeoutExpired
✅ Verification: Run python -m pytest tests/test_pdf_security.py and full test suite

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PR created automatically by Jules for task 8216287924626519256 started by @anchapin

Summary by Sourcery

Harden LaTeX-based PDF generation against RCE and DoS by enforcing secure subprocess flags and timeouts across converters and cover letter generation.

Bug Fixes:

• Prevent remote code execution by adding -no-shell-escape to pdflatex and --pdf-engine-opt=-no-shell-escape to pandoc-based PDF compilation paths.
• Mitigate denial-of-service hangs during PDF compilation by enforcing a 30-second timeout and handling subprocess.TimeoutExpired in LaTeX and Pandoc subprocess calls.

Enhancements:

• Extend PDF security test coverage to validate secure arguments, timeout behavior, and fallback logic in PDFConverter and CoverLetterGenerator.
• Document the new LaTeX subprocess security requirements and learnings in the Sentinel security log.

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[sourcery-ai]

Reviewer's Guide

This PR hardens LaTeX-based PDF generation against RCE and DoS by adding no-shell-escape flags and strict timeouts to pdflatex/pandoc subprocess calls, and introduces tests to verify secure behavior and document the sentinel finding.

Sequence diagram for secured LaTeX PDF compilation with timeout and no shell escape

sequenceDiagram
    actor User
    participant CoverLetterGenerator
    participant PdflatexProcess

    User->>CoverLetterGenerator: generate_cover_letter()
    CoverLetterGenerator->>CoverLetterGenerator: _compile_pdf(output_path, tex_content)
    CoverLetterGenerator->>PdflatexProcess: subprocess.Popen(["pdflatex", "-interaction=nonstopmode", "-no-shell-escape", tex_path.name])
    CoverLetterGenerator->>PdflatexProcess: communicate(timeout=30)

    alt subprocess.TimeoutExpired
        CoverLetterGenerator->>PdflatexProcess: kill()
        CoverLetterGenerator->>PdflatexProcess: communicate()
        CoverLetterGenerator-->>User: return False (PDF generation aborted)
    else process.returncode == 0 or output_path.exists()
        CoverLetterGenerator-->>User: return True (PDF generated securely)
    end

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File-Level Changes

Change	Details	Files
Harden pdflatex and pandoc subprocess calls in PDFConverter and CoverLetterGenerator with no-shell-escape flags and timeouts, returning failure on compilation hangs.	Add -no-shell-escape to all pdflatex invocations used for PDF compilation. Add --pdf-engine-opt=-no-shell-escape to pandoc invocations with xelatex as the PDF engine. Wrap subprocess.communicate calls with a 30-second timeout and handle subprocess.TimeoutExpired by killing the process, calling communicate again, and returning False. Preserve existing success checks based on process return code or output file existence while integrating timeout handling.	cli/pdf/converter.py cli/generators/cover_letter_generator.py
Extend test coverage to assert secure invocation parameters and timeout handling for LaTeX/PDF compilation paths.	Introduce MockConfig helper and import PDFConverter and CoverLetterGenerator into the test module. Add tests for PDFConverter pdflatex and pandoc compilation that verify no-shell-escape arguments, timeout usage, process.kill calls, and False return on timeout. Add tests for CoverLetterGenerator LaTeX and pandoc compilation (including pandoc fallback when pdflatex is missing) verifying secure flags, timeout handling, and failure behavior. Use unittest.mock.patch and side_effects on subprocess.Popen.communicate to simulate TimeoutExpired and normal completion flows.	tests/test_pdf_security.py
Update sentinel documentation with a new security incident entry describing the LaTeX subprocess execution vulnerability and its mitigation.	Document the missing no-shell-escape and timeout constraints as a critical LaTeX subprocess execution finding. Capture the security learning around shell execution risks and DoS via compilation hangs. Describe prevention guidance to always enforce no-shell-escape and strict timeouts with proper TimeoutExpired handling for LaTeX/Pandoc subprocesses.	.jules/sentinel.md

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[sourcery-ai]

Hey - I've left some high level feedback:

• The timeout handling logic for LaTeX/Pandoc subprocesses is duplicated in multiple methods; consider extracting a small helper to encapsulate the Popen + communicate(timeout) + TimeoutExpired/kill pattern for consistency and easier maintenance.
• The 30-second timeout is currently hard-coded in several places; it may be worth making this configurable (e.g., via a constant or config option) so it can be tuned without code changes and kept consistent across all PDF compilation paths.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The timeout handling logic for LaTeX/Pandoc subprocesses is duplicated in multiple methods; consider extracting a small helper to encapsulate the `Popen` + `communicate(timeout)` + `TimeoutExpired`/kill pattern for consistency and easier maintenance.
- The 30-second timeout is currently hard-coded in several places; it may be worth making this configurable (e.g., via a constant or config option) so it can be tuned without code changes and kept consistent across all PDF compilation paths.

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