🛡️ Sentinel: [CRITICAL] Fix LaTeX RCE via Shell Escape

[anchapin]

🚨 Severity: CRITICAL
💡 Vulnerability: PDF compilation commands lacked restricted execution flags (-no-shell-escape), allowing malicious LaTeX input to execute arbitrary system commands via shell escape.
🎯 Impact: An attacker could achieve Remote Code Execution (RCE) on the server.
🔧 Fix: Applied -no-shell-escape to pdflatex and --pdf-engine-opt=-no-shell-escape to pandoc. Added process timeout handling to fail securely.
✅ Verification: Tested PDF compilation functions to ensure flags are correctly applied and fallbacks work on timeout.

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PR created automatically by Jules for task 9643023613464355314 started by @anchapin

Summary by Sourcery

Harden LaTeX-based PDF generation against command execution and hangs by restricting shell access and enforcing timeouts on compilation processes.

Bug Fixes:

• Prevent remote code execution during LaTeX PDF compilation by adding no-shell-escape flags to pdflatex and pandoc invocations.
• Avoid indefinite hangs in PDF compilation by enforcing a timeout and failing securely when the LaTeX or pandoc process exceeds the limit.

Documentation:

• Extend Sentinel security notes with details of the LaTeX shell-escape RCE vulnerability and its mitigation.

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Reviewer's Guide

Adds hardened LaTeX/PDF compilation by disabling shell escape in pdflatex/pandoc and introducing timeouts for the external processes, plus documenting the security issue in Sentinel notes.

Flow diagram for hardened LaTeX PDF compilation with no shell escape and timeouts

flowchart TD
    start([Start _compile_pdf])
    try_pdflatex["Call subprocess.Popen pdflatex -interaction=nonstopmode -no-shell-escape"]
    pdflatex_comm["process.communicate(timeout=30)"]
    pdflatex_timeout{TimeoutExpired?}
    pdflatex_kill["process.kill() and process.communicate()"]
    pdflatex_fail["Return False"]
    pdflatex_success{pdflatex success or output_path exists?}
    set_pdf_true["pdf_created = True"]
    fallback_needed{Need pandoc fallback?}

    try_pandoc["Call subprocess.Popen pandoc --pdf-engine=xelatex --pdf-engine-opt=-no-shell-escape"]
    pandoc_comm["process.communicate(timeout=30)"]
    pandoc_timeout{TimeoutExpired?}
    pandoc_kill["process.kill() and process.communicate()"]
    pandoc_fail["Return False"]
    pandoc_success{pandoc success or output_path exists?}
    set_pdf_true_fallback["pdf_created = True"]
    end_node([End _compile_pdf])

    start --> try_pdflatex --> pdflatex_comm --> pdflatex_timeout
    pdflatex_timeout -- Yes --> pdflatex_kill --> pdflatex_fail
    pdflatex_timeout -- No --> pdflatex_success
    pdflatex_success -- Yes --> set_pdf_true --> end_node
    pdflatex_success -- No --> fallback_needed

    fallback_needed -- Yes --> try_pandoc --> pandoc_comm --> pandoc_timeout
    pandoc_timeout -- Yes --> pandoc_kill --> pandoc_fail
    pandoc_timeout -- No --> pandoc_success
    pandoc_success -- Yes --> set_pdf_true_fallback --> end_node
    pandoc_success -- No --> end_node

    fallback_needed -- No --> end_node

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File-Level Changes

Change	Details	Files
Harden cover letter PDF compilation against LaTeX-based RCE and hanging processes.	Add -no-shell-escape flag to pdflatex invocation to disable shell escapes. Switch subprocess.communicate to use a bounded timeout and kill the process on timeout, returning failure. Add --pdf-engine-opt=-no-shell-escape to pandoc fallback invocation to propagate shell-escape restrictions to the LaTeX engine. Apply the same shell-escape restriction and timeout handling patterns to both pdflatex and pandoc flows.	cli/generators/cover_letter_generator.py
Apply the same LaTeX PDF hardening (no shell escape + timeouts) to the generic PDF converter utilities.	Add -no-shell-escape flag to pdflatex in the converter path. Add communicate timeouts and process.kill() on TimeoutExpired, treating timeouts as failed compilations. Add --pdf-engine-opt=-no-shell-escape to pandoc invocation used by the converter, with the same timeout handling.	cli/pdf/converter.py
Document the newly discovered LaTeX shell-escape RCE in the security Sentinel record.	Add a dated Sentinel entry describing the root cause (missing restricted execution flags), key learning, and prevention pattern for LaTeX compilation commands.	.jules/sentinel.md

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