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

[anchapin]

🚨 Severity: CRITICAL
💡 Vulnerability: pdflatex and pandoc were executed without -no-shell-escape and timeouts in multiple modules (cli/pdf/converter.py and cli/generators/cover_letter_generator.py).
🎯 Impact: Allows Local File Inclusion (LFI) and Remote Code Execution (RCE) via LaTeX injections, and infinite loop/DoS attacks via missing timeouts.
🔧 Fix: Added -no-shell-escape and --pdf-engine-opt=-no-shell-escape arguments and implemented a 30s timeout with process kill handling.
✅ Verification: Ran python -m pytest tests/test_pdf_security.py and the full test suite to verify the timeout handling and correct CLI arguments.

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PR created automatically by Jules for task 8058454716389122478 started by @anchapin

Summary by Sourcery

Harden PDF generation against LaTeX-based RCE and DoS vectors by locking down pdflatex/pandoc execution and enforcing timeouts.

Bug Fixes:

• Disable LaTeX shell escapes in pdflatex and pandoc invocations used by the cover letter generator and generic PDF converter to prevent LFI/RCE via LaTeX input.
• Add 30-second timeouts with proper process termination for all LaTeX-related subprocess executions to avoid hangs and DoS conditions.

Documentation:

• Document the LaTeX RCE and DoS vulnerabilities and their mitigations in the Sentinel security log for future reference.

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[sourcery-ai]

Reviewer's Guide

Hardened LaTeX-based PDF generation by disabling shell escapes and adding robust timeouts around pdflatex/pandoc subprocesses, plus documenting the security fix in the Sentinel security log.

Sequence diagram for secured LaTeX PDF generation with timeout

sequenceDiagram
    participant PdfGenerator
    participant subprocess
    participant process

    PdfGenerator->>subprocess: Popen(["pdflatex", "-interaction=nonstopmode", "-no-shell-escape", tex_path.name])
    subprocess-->>PdfGenerator: process

    alt [within 30 seconds]
        PdfGenerator->>process: communicate(timeout=30)
        process-->>PdfGenerator: stdout, stderr
        PdfGenerator->>PdfGenerator: [check process.returncode or output_path.exists]
    else [timeout]
        PdfGenerator->>process: communicate(timeout=30)
        process--xPdfGenerator: TimeoutExpired
        PdfGenerator->>process: kill()
        PdfGenerator->>process: communicate()
        PdfGenerator-->>PdfGenerator: return False
    end

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File-Level Changes

Change	Details	Files
Hardened pdflatex and pandoc invocations in cover letter PDF generation.	Added -no-shell-escape flag to pdflatex subprocess calls to prevent LaTeX shell command execution. Added --pdf-engine-opt=-no-shell-escape to pandoc subprocess calls using xelatex. Wrapped subprocess.communicate with a 30s timeout, killing the process and returning failure on TimeoutExpired. Preserved existing success criteria by still checking both return code and PDF file existence.	cli/generators/cover_letter_generator.py
Hardened core PDF converter’s LaTeX compilation paths.	Updated pdflatex calls to include -no-shell-escape and set working directory explicitly as before. Updated pandoc calls to include --pdf-engine-opt=-no-shell-escape while retaining existing arguments. Introduced a 30s timeout around subprocess.communicate for both pdflatex and pandoc, with TimeoutExpired handling that kills the process, drains output, and returns False.	cli/pdf/converter.py
Documented the LaTeX RCE and DoS vulnerability and its mitigation in the Sentinel security log.	Added a new dated entry describing the lack of -no-shell-escape and timeouts as the root cause. Recorded the security learning around pdflatex shell escapes and the need for timeouts. Documented concrete prevention steps for future subprocess-based PDF generation code.	.jules/sentinel.md

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[sourcery-ai]

Hey - I've left some high level feedback:

• The subprocess timeout and kill logic is duplicated in four places; consider extracting a small helper function (e.g., run_with_timeout(cmd, cwd, timeout=30)) to centralize this behavior and reduce the risk of divergence in future changes.
• Right now a timeout simply returns False with no visibility; it may be helpful to log or surface a specific error message for timeout cases so operators can distinguish them from normal LaTeX failures.
• The 30-second timeout is currently a magic number; consider making it a named constant or configurable setting so it can be tuned without editing multiple call sites.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The subprocess timeout and kill logic is duplicated in four places; consider extracting a small helper function (e.g., `run_with_timeout(cmd, cwd, timeout=30)`) to centralize this behavior and reduce the risk of divergence in future changes.
- Right now a timeout simply returns `False` with no visibility; it may be helpful to log or surface a specific error message for timeout cases so operators can distinguish them from normal LaTeX failures.
- The 30-second timeout is currently a magic number; consider making it a named constant or configurable setting so it can be tuned without editing multiple call sites.

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