fix: update MathJax CDN from 2.7.5 to 2.7.9 (CVE-2023-39663)

[jignaciopm]

Summary

MathJax 2.7.5 is vulnerable to ReDoS (Regular Expression Denial of Service) via CVE-2023-39663. This updates all CDN references from jsdelivr to use MathJax 2.7.9 which includes the fix.

CVSS: 5.4 (Medium)

Context

MathJax is loaded via CDN (cdn.jsdelivr.net/npm/mathjax@2.7.5) in 8 files across LMS, CMS, discussion forums, and xblock v2 iframes. Version 2.7.5 is vulnerable to ReDoS which can cause denial of service when processing specially crafted mathematical expressions.

MathJax 2.7.9 is a patch release in the same 2.7.x line and is backwards compatible.

Files changed

• common/templates/mathjax_include.html — Main LMS template
• common/templates/xblock_v2/xblock_iframe.html — xblock v2 iframe
• cms/static/cms/js/require-config.js — Studio RequireJS config
• cms/djangoapps/pipeline_js/js/xmodule.js — Studio script loader
• common/static/common/js/discussion/mathjax_include.js — Discussion forums
• lms/static/lms/js/spec/main.js — LMS test spec
• cms/static/cms/js/spec/main.js — CMS test spec
• cms/static/cms/js/spec/main_squire.js — CMS test spec

Test plan

• Verify LaTeX formulas render correctly in LMS course content
• Verify formulas render in Studio preview
• Verify formulas render in discussion forums
• Verify xblock v2 iframe content renders formulas

References

• CVE-2023-39663
• MathJax 2.7.9 Release Notes

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