CVE-2019-9704: Vixie Cron before the 3.0pl1-133 Debian package allows local users to cause a denial of service (daemon crash)

Q: How do I fix CVE-2019-9704?

cron: upgrade to 3.0pl1-133; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2019-9704 being exploited?

CVE-2019-9704 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2019-9704 affect?

CVE-2019-9704 affects cron, fedora, debian linux. Severity is medium (CVSS 5.5). Vixie Cron before the 3.0pl1-133 Debian package allows local users to cause a denial of service (daemon crash) via a large crontab file because the calloc return value is not checked.

Q: How urgent is CVE-2019-9704?

Priority 32/100. On your watchlist

Routine

MEDIUM 5.5WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2019-9704 is a medium-severity flaw (CVSS 5.5) affecting cron, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Vixie Cron before the 3.0pl1-133 Debian package allows local users to cause a denial of service (daemon crash) via a large crontab file because the calloc return value is not checked.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 70%)
CISA exploited list	No
Weakness	CWE-252, CWE-476
Published	2019-03-12
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: cron project · debian · fedoraproject

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

Am I affected?

Timeline

2019-03-12 01:29 UTCPublished CVE record published
2026-06-17 02:44 UTCUpdated Record last modified

cron project cron UPGRADE

Affected: < 3.0pl1-133

Fixed in: 3.0pl1-133

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.0pl1-133 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cron

Note

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

fedoraproject fedora MITIGATE

Affected: 29

Fixed in: no fixed release known

Safe to downgrade to: a release before 29

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

debian debian linux MITIGATE

Affected: 8.0 · 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2019-9704?

cron: upgrade to 3.0pl1-133; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2019-9704 being exploited?

CVE-2019-9704 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-2019-9704 affect?

CVE-2019-9704 affects cron, fedora, debian linux. Severity is medium (CVSS 5.5). Vixie Cron before the 3.0pl1-133 Debian package allows local users to cause a denial of service (daemon crash) via a large crontab file because the calloc return value is not checked.

How urgent is CVE-2019-9704?

Priority 32/100. On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2019-9706 MEDIUM 5.5 DOWNGRADE MITIGATE Vixie Cron before the 3.0pl1-133 Debian package allows local users to cause a denial of service (use-after-fre
CVE-2019-9705 MEDIUM 5.5 UPGRADE MITIGATE Vixie Cron before the 3.0pl1-133 Debian package allows local users to cause a denial of service (memory consum
CVE-2017-9525 MEDIUM 6.7 UPGRADE MITIGATE In the cron package through 3.0pl1-128 on Debian, and through 3.0pl1-128ubuntu2 on Ubuntu, the postinst mainta

References

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