# CVE-2026-63275: LibreOffice stack buffer overflow in CFF font hint handling

Source: https://junglewise.ai/threats/cve-2026-63275-libreoffice-can-read-cff-fonts-which-may-be-embedded-in-documents  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-22. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-63275 · Severity: info · Published 2026-09-22

LibreOffice, a widely used open-source office suite, can read embedded CFF fonts in documents. A stack buffer overflow in font hint processing could allow an attacker to crash the application or potentially execute code by crafting a malicious document with a specially formatted CFF font. Users who open untrusted documents are at risk.

Technologies: [LibreOffice](https://junglewise.ai/threats/technologies/libreoffice-libreoffice). Vendors: [LibreOffice](https://junglewise.ai/threats/vendors/libreoffice).

## Quick answers

**Is CVE-2026-63275 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-63275 being exploited in the wild.

**How severe is CVE-2026-63275?** Informational severity, published 22 September 2026.

**Which products and versions are affected?** LibreOffice before 26.2.5.

**Is there a fix for CVE-2026-63275?** A patch was published on 2026-09-22: Fixed in LibreOffice 26.2.5 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-63275 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-63275?** Check whether you run LibreOffice at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A stack buffer overflow exists in LibreOffice's CFF font parsing when reading glyph hints. The hint count validation checked against an incorrect bound, allowing a glyph to declare more hints than the fixed-size array can hold, resulting in a stack write overflow. An attacker can trigger this via a malicious document containing an embedded CFF font with an excessive hint count.

## Affected products

- LibreOffice LibreOffice before 26.2.5

## Timeline

- 2026-09-21: disclosed
- 2026-09-22: patched: Fixed in LibreOffice 26.2.5

## References

- [https://www.libreoffice.org/about-us/security/advisories/cve-2026-63275](https://www.libreoffice.org/about-us/security/advisories/cve-2026-63275)

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- [LibreOffice heap buffer overflow in WMF text record import](https://junglewise.ai/threats/cve-2026-63272-libreoffice-can-import-wmf-graphics-which-may-be-embedded-in)