CVE-2018-20304: wbook_addworksheet in workbook.c in libexcel.a in libexcel 0.01 allows attackers to cause a denial of service

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MEDIUM 6.5DOWNGRADE

CVE-2018-20304 is a medium-severity flaw (CVSS 6.5) affecting libexcel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

wbook_addworksheet in workbook.c in libexcel.a in libexcel 0.01 allows attackers to cause a denial of service (SEGV) via a long second argument. NOTE: this is not a Microsoft product.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 42%)
CISA exploited list	No
Weakness	CWE-119
Published	2018-12-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: libexcel project

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

Am I affected?

Timeline

2018-12-20 00:29 UTCPublished CVE record published
2026-06-17 01:52 UTCUpdated Record last modified

libexcel project libexcel DOWNGRADE

Affected: 0.01

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.01

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.01 (Debian / Ubuntu)

apt-cache madison libexcel sudo apt install libexcel=<VERSION_BEFORE_0.01> sudo apt-mark hold libexcel

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libexcel sudo dnf downgrade libexcel-<VERSION_BEFORE_0.01> sudo dnf versionlock add libexcel

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.

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-2018-20304?

libexcel: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-20304 being exploited?

CVE-2018-20304 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-2018-20304 affect?

CVE-2018-20304 affects libexcel. Severity is medium (CVSS 6.5). wbook_addworksheet in workbook.c in libexcel.a in libexcel 0.01 allows attackers to cause a denial of service (SEGV) via a long second argument. NOTE: this is not a Microsoft product.

How urgent is CVE-2018-20304?

Priority 42/100. Public exploit reference

Related CVEs

CVE-2018-20213 HIGH 7.5 DOWNGRADE wbook_addworksheet in workbook.c in libexcel.a in libexcel 0.01 allows attackers to cause a denial of service

References

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