Bug 2496640 (CVE-2026-56001) - CVE-2026-56001 libXfont2: BitmapScaleBitmaps Integer Overflow Heap Buffer Overflow
Summary: CVE-2026-56001 libXfont2: BitmapScaleBitmaps Integer Overflow Heap Buffer Ove...
Keywords:
Status: NEW
Alias: CVE-2026-56001
Deadline: 2026-07-08
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-02 18:31 UTC by OSIDB Bzimport
Modified: 2026-07-10 19:13 UTC (History)
5 users (show)

Fixed In Version:
Clone Of:
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Description OSIDB Bzimport 2026-07-02 18:31:34 UTC 
In libXfont2's BitmapScaleBitmaps() function, a 32-bit variable keeps the number of bytes to allocate. If the value overflows due to excessive per-glyph byte counts, the resulting calloc() allocates a buffer too small for the subsequent operations. An attacker can trigger this by loading a crafted PCF font via SetFontPath + OpenFont at a scale factor that inflates per-glyph byte counts.
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