fix: backport vendored pdf.js bump to 5.7.284 (GHSA-mj74-gfq3-2v9f)#322
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jignaciopm merged 1 commit intoJul 17, 2026
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The previous vendored pdf.js was 1.0.907 (May 2013), four major versions behind upstream and within the range covered by Mozilla's GHSA-wgrm-67xf-hhpq (arbitrary JavaScript execution upon opening a malicious PDF). 5.7.284 is well past the >= 4.2.67 fix line. The replacement comes from Mozilla's prebuilt `pdfjs-5.7.284-legacy-dist.zip` GitHub Release artifact rather than the `pdfjs-dist` npm package because the npm package is library-only -- it ships `pdf.mjs` plus a bare `PDFViewer` component class, but no `viewer.html` / `viewer.mjs` / `viewer.css` / locale files. A full npm integration would mean rewriting the viewer page against the bare component, which is appropriate as a non-security follow-up but not as the fix here. The viewer page (`lms/templates/pdf_viewer.html`) is rewritten as a Mako adaptation of upstream `web/viewer.html`. A `<base href>` makes the viewer's relative asset URLs resolve against the vendored copy. The analytics shim (`lms/static/js/pdf-analytics.js`) is rewritten in vanilla JS against `PDFViewerApplication.eventBus`. Four analytics events (`textbook.pdf.thumbnails.toggled`, `textbook.pdf.thumbnail.navigated`, `textbook.pdf.outline.toggled`, `textbook.pdf.page.scrolled`) no longer fire because the corresponding UI elements were refactored away in pdf.js 4.x's Views Manager redesign. A new `scripts/refresh-pdfjs-vendor.sh` is the tool for future bumps: update PDFJS_VERSION + PDFJS_LEGACY_ZIP_SHA256, re-run, commit. Closes GHSA-mj74-gfq3-2v9f.
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Summary
Context
The official security release on July 7, 2026 patched Ulmo and Verawood but did not include Teak. Since the vendored pdf.js files are identical across all three release branches, this cherry-pick applies cleanly with no conflicts.
The previous vendored pdf.js was v1.0.907 (May 2013), four major versions behind upstream and within the range covered by Mozilla's GHSA-wgrm-67xf-hhpq (arbitrary JavaScript execution upon opening a malicious PDF). v5.7.284 is well past the >= 4.2.67 fix line.
Test plan
pdfjsLib.versionin browser console returns"5.7.284"