🛡️ Sentinel: [CRITICAL] Fix LaTeX Injection RCE and DoS in PDF Compilation

[anchapin]

🚨 Severity: CRITICAL
💡 Vulnerability: LaTeX injection RCE and DoS without timeouts in CoverLetterGenerator and PDFConverter
🎯 Impact: Arbitrary code execution or Denial of Service
🔧 Fix: Add -no-shell-escape flags and 30s timeouts
✅ Verification: Tests pass.

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PR created automatically by Jules for task 9727106323628115774 started by @anchapin

Summary by Sourcery

Harden LaTeX-based PDF generation against remote code execution and hangs by restricting compiler capabilities and enforcing time-bounded execution.

Bug Fixes:

• Disable LaTeX shell escape in pdflatex and pandoc PDF compilation paths in the cover letter generator and generic PDF converter to prevent command execution via injected LaTeX.
• Add 30-second timeouts and cleanup on LaTeX and pandoc compilation to avoid indefinite hangs and associated Denial of Service conditions.

Documentation:

• Update Sentinel security notes with a new entry documenting the LaTeX injection RCE and DoS vulnerability, its root cause, and the applied mitigations.

Tests:

• Extend PDF security tests to verify that pdflatex and pandoc are invoked with no-shell-escape options and that compilation correctly times out and terminates on long-running processes.

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[sourcery-ai]

Reviewer's Guide

Adds defensive flags and timeouts around LaTeX/PDF compilation in PDFConverter and CoverLetterGenerator to mitigate LaTeX injection RCE and DoS, and introduces tests plus Sentinel documentation for these behaviors.

Sequence diagram for secured LaTeX PDF compilation with flags and timeout

sequenceDiagram
    participant Caller
    participant CoverLetterGenerator
    participant PDFConverter
    participant subprocess

    Caller->>CoverLetterGenerator: _compile_pdf(output_path, tex_content)
    CoverLetterGenerator->>subprocess: Popen(["pdflatex", "-interaction=nonstopmode", "-no-shell-escape", tex_path.name])
    alt pdflatex completes within 30s
        CoverLetterGenerator->>subprocess: process.communicate(timeout=30)
        subprocess-->>CoverLetterGenerator: stdout, stderr
        CoverLetterGenerator-->>Caller: pdf_created or fallback to pandoc
    else pdflatex times out
        CoverLetterGenerator->>subprocess: process.kill()
        CoverLetterGenerator->>subprocess: process.communicate()
        CoverLetterGenerator-->>Caller: False
    end

    Caller->>PDFConverter: _compile_pdflatex(output_path, tex_path, working_dir)
    PDFConverter->>subprocess: Popen(["pdflatex", "-interaction=nonstopmode", "-no-shell-escape", tex_path.name])
    alt pdflatex completes within 30s
        PDFConverter->>subprocess: process.communicate(timeout=30)
        subprocess-->>PDFConverter: stdout, stderr
        PDFConverter-->>Caller: True
    else pdflatex times out
        PDFConverter->>subprocess: process.kill()
        PDFConverter->>subprocess: process.communicate()
        PDFConverter-->>Caller: False
    end

    Caller->>PDFConverter: _compile_pandoc(output_path, tex_path, working_dir)
    PDFConverter->>subprocess: Popen(["pandoc", tex_path, "-o", output_path, "--pdf-engine=xelatex", "--pdf-engine-opt=-no-shell-escape"]) 
    alt pandoc completes within 30s
        PDFConverter->>subprocess: process.communicate(timeout=30)
        subprocess-->>PDFConverter: stdout, stderr
        PDFConverter-->>Caller: True
    else pandoc times out
        PDFConverter->>subprocess: process.kill()
        PDFConverter->>subprocess: process.communicate()
        PDFConverter-->>Caller: False
    end

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File-Level Changes

Change	Details	Files
Harden pdflatex and pandoc invocation in CoverLetterGenerator against RCE and DoS.	Add -no-shell-escape to pdflatex CLI arguments when compiling cover letter PDFs. Wrap pdflatex communicate() with a 30-second timeout, killing the process and returning False on TimeoutExpired. Extend the pandoc fallback invocation to pass --pdf-engine-opt=-no-shell-escape to disable shell escapes in the LaTeX engine. Add a 30-second timeout (with kill and False return) around pandoc communicate() to prevent hanging compilers.	cli/generators/cover_letter_generator.py
Harden pdflatex and pandoc invocation in generic PDFConverter against RCE and DoS.	Add -no-shell-escape to pdflatex CLI arguments for TeX compilation. Add a 30-second timeout around pdflatex communicate(), killing the process and returning False on TimeoutExpired to indicate failure. Extend pandoc invocation to include --pdf-engine-opt=-no-shell-escape when using xelatex as the PDF engine. Add a 30-second timeout around pandoc communicate(), killing the process and returning False on TimeoutExpired to signal failure.	cli/pdf/converter.py
Add regression tests to validate flags and timeout behavior for LaTeX and PDF compilation flows.	Introduce tests that mock subprocess.Popen for PDFConverter pdflatex and pandoc paths, asserting 30-second timeouts trigger kill() and False return when outputs do not exist. Add tests that verify -no-shell-escape and --pdf-engine-opt=-no-shell-escape are present in pdflatex and pandoc commands for PDFConverter. Introduce tests for CoverLetterGenerator._compile_pdf that set up minimal config/env, assert 30-second timeout kills pdflatex and returns False, and confirm -no-shell-escape/-interaction flags are present in normal invocations.	tests/test_pdf_security.py
Document the new LaTeX injection mitigation in Sentinel security log.	Append a new Sentinel entry describing the prior vulnerability (missing -no-shell-escape and timeouts), the learning, and the prevention guidelines for LaTeX compilation. Clarify that pdflatex and pandoc must always be invoked with shell escapes disabled and with enforced timeouts and cleanup.	.jules/sentinel.md

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