Summary
It was discovered that libXfont incorrectly handled scaling bitmap
fonts, leading to a heap buffer overflow. An attacker able to access
the X server could use this issue to cause libXfont to crash,
resulting in a denial of service, or possibly execute arbitrary code.
(CVE-2026-56001)
It was discovered that libXfont did not properly check glyph bounds
when reading PCF fonts, leading to a heap buffer overflow. An
authenticated X client could use this issue to cause libXfont to
crash, resulting in a denial of service, or possibly execute arbitrary
code. (CVE-2026-56002)
It was discovered that libXfont did not properly check the size of the
property buffer when parsing PCF fonts, leading to a heap buffer
overflow. An authenticated X client could use this issue to cause
libXfont to crash, resulting in a denial of service, or possibly
execute arbitrary code. (CVE-2026-56003)
Fixed packages 7
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 22.04 LTS 22.04:LTS | libxfont | 1:2.0.5-1ubuntu0.2 |
| Ubuntu · 24.04 LTS 24.04:LTS | libxfont | 1:2.0.6-1+deb13u1build0.24.04.2 |
| Ubuntu · 26.04 LTS 26.04:LTS | libxfont | 1:2.0.6-2ubuntu0.2 |
| Ubuntu · Pro 14.04 LTS Pro:14.04:LTS | libxfont | 1:1.4.7-1ubuntu0.4+esm2 |
| Ubuntu · Pro 16.04 LTS Pro:16.04:LTS | libxfont | 1:1.5.1-1ubuntu0.16.04.4+esm2 |
| Ubuntu · Pro 18.04 LTS Pro:18.04:LTS | libxfont | 1:2.0.3-1ubuntu0.1~esm2 |
| Ubuntu · Pro 20.04 LTS Pro:20.04:LTS | libxfont | 1:2.0.3-1ubuntu0.20.04.1~esm2 |
Vulnerabilities 4
-
High 8.5
libXfont2 BitmapScaleBitmaps Integer Overflow Heap Buffer Overflow
A heap buffer overflow in BitmapScaleBitmaps in libXfont2 before 2.0.8 due to an overflowing 32bit size could be used by attackers able to access the X Server to execute code within the X server cont
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High 8.5
libXfont2 PCF Font Parsing Heap Buffer Overflow
A heap bufferflow in pcfReadFont() due to missing glyph bounds checking in libXfont2 before 2.0.8 allows attackers authenticated as X client to execute code within the X server.
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High 8.5
libXfont2 computeProps Property Buffer Heap Buffer Overflow
A heap buffer overflow due to missing size checking in the property buffer when parsing PCF files in libXfont2 ComputeScaledProperties() before libXfont2 before 2.0.8 could be used by attackers using authenticated X clients to execute code within the X server.
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Unscored —
In libXfont before 1.5.4 and libXfont2 before 2.0.3, a local attacker can open (but not read) files on the system as ro…