CVE-2017-9525

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.

Published: 2017-06-09 Last update: 2026-05-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2017-9525 is rated Low Risk (33/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2017-9525

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-05-12 0.04% 0.06% +0.01%
2 2025-03-17 0.06% 0.04% -0.02%
3 2023-03-07 — 0.06% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2017-9525

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.7 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.8 5.9 [email protected]
6.9 2.0 MEDIUM
AV:L/AC:M/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.4 10.0 [email protected]

Weakness enumeration for CVE-2017-9525

OS Trackers for CVE-2017-9525

vendor priority summary link
debian not yet assigned CVE-2017-9525 not yet assigned priority: Debian including 2 source packages (cron, systemd-cron), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 9, open 1. https://security-tracker.debian.org/tracker/CVE-2017-9525
ubuntu low CVE-2017-9525 low priority: Ubuntu including 1 source packages (cron), 22 status rows across 22 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial, yakkety, zesty): not-affected 13, ignored 5, released 3, needed 1. https://ubuntu.com/security/CVE-2017-9525

Affected software / configurations for CVE-2017-9525

Vendor Product Version Raw CPE
cron_project cron <= 3.0pl1-128. cpe:2.3:a:cron_project:cron:*:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

References for CVE-2017-9525

URL Tags
http://bugs.debian.org/864466 Issue Tracking Third Party Advisory Vendor Advisory
http://www.openwall.com/lists/oss-security/2017/06/08/3 Mailing List Third Party Advisory
http://www.securitytracker.com/id/1038651 Third Party Advisory VDB Entry
https://lists.debian.org/debian-lts-announce/2019/03/msg00025.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/10/msg00029.html Mailing List Third Party Advisory
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