Summary
X.Org X11 libXfont2 runtime library
Security Fix(es):
* libxfont2: Font Server Client encoding[] Out-Of-Bounds Read/Write (CVE-2026-59679)
* libxfonts2: libXfont2: Privilege Escalation via Heap Buffer Overflow in Font Server Client (CVE-2026-44950)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Fixed packages 2
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux · 10 | libXfont2 | 2.0.6-5.el10_2.3 |
| AlmaLinux · 10 | libXfont2-devel | 2.0.6-5.el10_2.3 |
Vulnerabilities 2
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Critical 9.0
fs_read_glyphs() heap buffer overflow via cumulative glyph data overflow in libXfont2
fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) copies each glyph's bitmap into a single buffer. Existing checks validates only that the source slice (position, length) lies within the source bitmap buffer. It does not check whether the…
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Critical 9.0
fs_read_glyphs() heap OOB read/write via encoding array index mismatch in libXfont2
fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) indexes the per-character encoding[] array using num_chars from the FS_QueryXBitmaps16 reply, but that array was allocated with a size derived from num_extents in the separate FS_QueryXExt…