What is CVE-2026-4430?

CVE-2026-4430 is a high-severity vulnerability in Libreoffice, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2026-05-07.

How severe is CVE-2026-4430?

High severity. CVSS v3 base score is 7.8 out of 10.

Buffer overflow in Libreoffice

CVE-2026-4430

Out-of-bounds write vulnerability in The Document Foundation LibreOffice via crafted OOXML documents with mismatched encryption salt parameters. This issue affects LibreOffice: from 26.2 before 26.2.3, from 25.8 before 25.8.7.

Vulnerability class: Buffer Overflow

Published 2026-05-07 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.001 (1.2th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 1st percentile — 1.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: +0.000

Affected products

Libreoffice
The Document Foundation Libreoffice — versions 26.2, 25.8

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

www.libreoffice.org/about-us/security/advisories/cve-2026-4430 (Vendor Advisory)

Frequently asked questions

What is CVE-2026-4430?: CVE-2026-4430 is a high-severity vulnerability in Libreoffice, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2026-05-07.
How severe is CVE-2026-4430?: High severity. CVSS v3 base score is 7.8 out of 10.