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

[anchapin]

🚨 Severity: CRITICAL
💡 Vulnerability: PDF compilation commands (pdflatex/pandoc) lacked restricted execution flags and timeouts, allowing arbitrary command execution (RCE) via write18 and Denial of Service (DoS) via process hanging.
🎯 Impact: Malicious LaTeX input could execute arbitrary shell commands on the host system or consume all resources by hanging the process indefinitely.
🔧 Fix: Added -no-shell-escape flag to pdflatex and --pdf-engine-opt=-no-shell-escape to pandoc. Implemented subprocess.communicate(timeout=30) to enforce execution limits.
✅ Verification: Run the test suite (make test) and verify that compilation commands are correctly sanitized and time out as expected.

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PR created automatically by Jules for task 5865900579289697483 started by @anchapin

Summary by Sourcery

Harden PDF compilation by restricting LaTeX shell execution and enforcing timeouts on external processes.

Bug Fixes:

• Disable LaTeX shell escape in pdflatex and pandoc PDF compilation to prevent remote code execution.
• Add execution timeouts and termination handling for PDF compilation subprocesses to mitigate denial-of-service hangs.

Documentation:

• Document the RCE and DoS vulnerability in PDF compilation and the corresponding mitigations in the Sentinel security log.

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Reviewer's Guide

Adds hardened PDF compilation by disabling LaTeX shell escape and enforcing execution timeouts for pdflatex/pandoc in both the cover letter generator and shared PDF converter, and documents the security fix in the Sentinel log.

Sequence diagram for hardened PDF compilation with timeout and no_shell_escape

sequenceDiagram
    participant CoverLetterGenerator
    participant subprocess
    participant pdflatex

    CoverLetterGenerator->>subprocess: Popen(pdflatex -interaction=nonstopmode -no-shell-escape)
    subprocess-->>pdflatex: start_process
    CoverLetterGenerator->>pdflatex: process.communicate(timeout=30)

    alt compilation completes
        pdflatex-->>CoverLetterGenerator: stdout, stderr (returncode == 0)
        CoverLetterGenerator->>CoverLetterGenerator: set pdf_created True
    else subprocess.TimeoutExpired
        pdflatex-->>CoverLetterGenerator: TimeoutExpired
        CoverLetterGenerator->>pdflatex: process.kill()
        pdflatex-->>CoverLetterGenerator: stdout, stderr after kill
        CoverLetterGenerator->>CoverLetterGenerator: return False
    end

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Sequence diagram for hardened Pandoc PDF compilation with timeout and no_shell_escape

sequenceDiagram
    participant PDFConverter
    participant subprocess
    participant pandoc

    PDFConverter->>subprocess: Popen(pandoc --pdf-engine=xelatex --pdf-engine-opt=-no-shell-escape)
    subprocess-->>pandoc: start_process
    PDFConverter->>pandoc: process.communicate(timeout=30)

    alt compilation completes
        pandoc-->>PDFConverter: stdout, stderr (returncode == 0)
        PDFConverter->>PDFConverter: return True
    else subprocess.TimeoutExpired
        pandoc-->>PDFConverter: TimeoutExpired
        PDFConverter->>pandoc: process.kill()
        pandoc-->>PDFConverter: stdout, stderr after kill
        PDFConverter->>PDFConverter: return False
    end

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File-Level Changes

Change	Details	Files
Harden pdflatex invocation in cover letter generator and PDF converter to prevent shell command execution and hangs.	Add -no-shell-escape flag to all pdflatex subprocess calls Wrap subprocess.communicate with a 30-second timeout and kill on TimeoutExpired Ensure compilation failure is signaled (return False) when a timeout occurs instead of hanging or continuing	cli/generators/cover_letter_generator.py cli/pdf/converter.py
Harden pandoc-based PDF compilation fallback to disable shell escape and enforce timeouts.	Add --pdf-engine-opt=-no-shell-escape to pandoc invocations using xelatex as the PDF engine Apply the same 30-second subprocess.communicate timeout and kill-on-timeout behavior to pandoc processes Return False when pandoc compilation times out to avoid false positives	cli/generators/cover_letter_generator.py cli/pdf/converter.py
Document the RCE/DoS vulnerability and applied mitigations in the Sentinel security log.	Append a new Sentinel entry describing the missing shell-escape restrictions and timeouts Record learnings about consistently enforcing security controls across modules Document prevention guidance for LaTeX processing and subprocess timeouts	.jules/sentinel.md

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