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CRITICAL

CVE-2026-44950

CVSS v3

9

CRITICAL

EPSS Score

0.4 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

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 running destination cursor has exceeded the allocation. A malicious font server can send overlapping source offsets -- for example 1000 glyphs each referencing {position:0, length:64} with nbytes=64. Each individual source range passes the

Technical details

Published
2026-09-10
Last Modified
2026-09-10

Frequently asked questions

What is CVE-2026-44950?

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 running destination cursor has exceeded the allocation. A malicious font server can send overlapping source offsets -- for example 1000 glyphs each referencing {position:0, length:64} with nbytes=64. Each individual source range passes the

Is CVE-2026-44950 actively exploited?

Active exploitation of CVE-2026-44950 has not been confirmed. Its EPSS score was 0.4% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-44950?

CVE-2026-44950 has a CVSS v3 base score of 9 (CRITICAL severity).

Is CVE-2026-44950 affecting your environment?

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