---
id: CVE-2026-63276
title: >-
  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
summary: >-
  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 we…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:P'
cwe:
  - CWE-787
  - CWE-121
vendor: The Document Foundation
product: LibreOffice
affected:
  - LibreOffice >= 26.2 < < 26.2.5
published: '2026-09-22'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:09:32.273'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63276'
references:
  - url: 'https://www.libreoffice.org/about-us/security/advisories/cve-2026-63276'
    label: security@documentfoundation.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63276.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-63276'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2538242'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-63276'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63276'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-22T12:21:19.661928Z'
cvssSource: cna
ingestedAt: '2026-09-22T12:03:01.596Z'
scores:
  cna: 5.4
  vendor: 7.3
epss: 0.00167
epssPercentile: 0.06397
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-09-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63276.json)