CVE-2017-9525: In the cron package through 3.0pl1-128 on Debian, and through 3.0pl1-128ubuntu2 on Ubuntu, the postinst mainta

Q: How do I fix CVE-2017-9525?

cron: upgrade to newer than 3.0pl1-128.; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2017-9525 being exploited?

CVE-2017-9525 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-2017-9525 affect?

CVE-2017-9525 affects cron, debian linux. Severity is medium (CVSS 6.7). In the cron package through 3.0pl1-128 on Debian, and through 3.0pl1-128ubuntu2 on Ubuntu, the postinst maintainer script allows for group-crontab-to-root privilege escalation via symlink attacks against unsafe usage of the chown and chmod

Q: How urgent is CVE-2017-9525?

Priority 40/100. On your watchlist

This month

MEDIUM 6.7WATCHLISTUPGRADEMITIGATE

CVE-2017-9525 is a medium-severity flaw (CVSS 6.7) affecting cron, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the cron package through 3.0pl1-128 on Debian, and through 3.0pl1-128ubuntu2 on Ubuntu, the postinst maintainer script allows for group-crontab-to-root privilege escalation via symlink attacks against unsafe usage of the chown and chmod programs.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.7 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.6% (top 54%)
CISA exploited list	No
Weakness	CWE-59
Published	2017-06-09
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2017-06-09 16:29 UTCPublished CVE record published
2026-06-17 01:28 UTCUpdated Record last modified

cron project cron UPGRADE

Affected: <= 3.0pl1-128.

Fixed in: newer than 3.0pl1-128.

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 3.0pl1-128. (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.

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-2017-9525?

cron: upgrade to newer than 3.0pl1-128.; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-9525 being exploited?

CVE-2017-9525 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-2017-9525 affect?

CVE-2017-9525 affects cron, debian linux. Severity is medium (CVSS 6.7). In the cron package through 3.0pl1-128 on Debian, and through 3.0pl1-128ubuntu2 on Ubuntu, the postinst maintainer script allows for group-crontab-to-root privilege escalation via symlink attacks against unsafe usage of the chown and chmod

How urgent is CVE-2017-9525?

Priority 40/100. On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities

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References

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