CVE-2026-4430: Out-of-bounds write vulnerability in The Document Foundation LibreOffice via crafted OOXML documents with mism

Routine

HIGH 7.8UPGRADE

CVE-2026-4430 is a high-severity flaw (CVSS 7.8) affecting libreoffice. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.1% (top 100%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-05-07
Last modified	2026-06-17

Publisher (CNA): Document Foundation, The · Vendor: libreoffice

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-07 08:16 UTCPublished CVE record published
2026-06-17 10:56 UTCUpdated Record last modified

libreoffice libreoffice UPGRADE

Affected: >= 25.8.0.0 and < 25.8.7.0 · >= 26.2.0.0 and < 26.2.3.0

Fixed in: 25.8.7.0, 26.2.3.0

Safe to downgrade to: a release before 25.8.0.0

1. Check installed version

apt-cache policy libreoffice || rpm -q libreoffice || libreoffice --version

2. UPGRADE to 25.8.7.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libreoffice

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libreoffice

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 25.8.0.0 (Debian / Ubuntu)

apt-cache madison libreoffice sudo apt install libreoffice=<VERSION_BEFORE_25.8.0.0> sudo apt-mark hold libreoffice

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libreoffice sudo dnf downgrade libreoffice-<VERSION_BEFORE_25.8.0.0> sudo dnf versionlock add libreoffice

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:28290] Moderate: libreoffice security update 2026-07-13

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-4430?

libreoffice: upgrade to 25.8.7.0, 26.2.3.0. Exact commands for each OS are on this page.

Is CVE-2026-4430 being exploited?

CVE-2026-4430 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-4430 affect?

CVE-2026-4430 affects libreoffice. Severity is high (CVSS 7.8). 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.

How urgent is CVE-2026-4430?

Priority 27/100. High severity

Software pages

LibreOffice vulnerabilities

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References

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