CVE-2026-63276: The Document Foundation Libreoffice

Medium severity, CVSS 5.4. EPSS: 0.2% chance of exploitation in the next 30 days.

LibreOffice converts CFF fonts to Type 1 when it subsets a font, which happens when a document is exported to PDF, and CFF fonts may be embedded in documents. A stack buffer overflow existed in that conversion. The converted operators were written into a fixed size buffer with no check that they still fit, so a glyph emitting many operators wrote past the end of the buffer. In fixed versions the remaining capacity is tracked and the conversion stops when it is used up.

Affected products

• The Document Foundation Libreoffice: from 26.2, before 26.2.5 (fixed in 26.2.5)

Published 2026-09-22. Last modified 2026-09-22.