Public bug reported:
Affects: fonts-katex (Ubuntu 26.04 LTS / Debian)
Package Version: 0.16.10+~cs6.1.0-5ubuntu1
Architecture: all
Severity: Medium
=== SUMMARY ===
The fonts-katex package installs 42 compressed web font files (.woff and
.woff2) directly into `/usr/share/fonts/truetype/katex/`.
According to Debian/Ubuntu font packaging guidelines,
`/usr/share/fonts/` is scanned globally by fontconfig for desktop
rasterization. Shipping raw web browser formats (.woff/.woff2) in system
desktop font paths causes fontconfig to index them as general-purpose
fallback fonts.
When desktop toolkits (such as Qt 6 / QML) perform character fallback
queries for geometric or mathematical glyphs (such as U+25CF '●'),
fontconfig attempts to evaluate `KaTeX_AMS-Regular.woff`, triggering a
fatal SIGSEGV in libfontconfig.so.1 due to unsupported or malformed
table offsets.
=== INSTALLED FILES IN DESKTOP PATH ===
$ dpkg -L fonts-katex | grep -E '\.woff|\.woff2' | head -n 10
/usr/share/fonts/truetype/katex/KaTeX_AMS-Regular.woff
/usr/share/fonts/truetype/katex/KaTeX_AMS-Regular.woff2
/usr/share/fonts/truetype/katex/KaTeX_Caligraphic-Bold.woff
/usr/share/fonts/truetype/katex/KaTeX_Caligraphic-Bold.woff2
/usr/share/fonts/truetype/katex/KaTeX_Caligraphic-Regular.woff
/usr/share/fonts/truetype/katex/KaTeX_Caligraphic-Regular.woff2
/usr/share/fonts/truetype/katex/KaTeX_Fraktur-Bold.woff
/usr/share/fonts/truetype/katex/KaTeX_Fraktur-Bold.woff2
/usr/share/fonts/truetype/katex/KaTeX_Fraktur-Regular.woff
/usr/share/fonts/truetype/katex/KaTeX_Fraktur-Regular.woff2
=== IMPACT ===
Any system with fonts-katex installed is vulnerable to desktop crashes whenever
an application requests glyph fallback that fontconfig matches against KaTeX
.woff files. In KDE Plasma, this completely breaks `kscreenlocker_greet` when
rendering password fields.
=== PROPOSED FIX ===
1. Web fonts (.woff, .woff2) should be installed into web/javascript asset
directories (e.g., `/usr/share/javascript/katex/fonts/`), not
`/usr/share/fonts/truetype/`.
2. Only true desktop font formats (TTF/OTF), if explicitly needed by desktop
applications, should reside under `/usr/share/fonts/`.
** Affects: node-katex (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2168515
Title:
Web fonts (.woff / .woff2) installed to /usr/share/fonts/truetype/
trigger desktop font fallback crashes
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