Quick answers
- Is CVE-2026-63276 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-63276 being exploited in the wild.
- How severe is CVE-2026-63276?
- Informational severity, published 22 September 2026.
- Which products and versions are affected?
- LibreOffice before 26.2.5.
- Is there a fix for CVE-2026-63276?
- A patch was published on 2026-09-21: 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-2026-63276 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-63276?
- 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 to Type 1 font conversion routine, which occurs during PDF export when fonts are subsetted. Converted font operators are written into a fixed-size buffer without bounds checking; a glyph emitting many operators will overflow the stack buffer. The attack vector is opening a malicious document with embedded CFF fonts and exporting to PDF.
Affected products
- LibreOffice LibreOffice before 26.2.5
Timeline
- 2026-09-21: disclosed
- 2026-09-21: patched: Fixed in LibreOffice 26.2.5