// For flags

CVE-2018-15687

systemd: chown_one() can dereference symlinks

Severity Score

7.0
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

2
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track*
*SSVC
Descriptions

A race condition in chown_one() of systemd allows an attacker to cause systemd to set arbitrary permissions on arbitrary files. Affected releases are systemd versions up to and including 239.

Una condición de carrera en chown_one() en systemd permite que un atacante provoque que systemd establezca permisos arbitrarios en archivos arbitrarios. Las versiones afectadas de systemd son todas hasta la 239 incluida.

USN-3816-1 fixed several vulnerabilities in systemd. However, the fix for CVE-2018-6954 was not sufficient. This update provides the remaining fixes. Jann Horn discovered that unit_deserialize incorrectly handled status messages above a certain length. A local attacker could potentially exploit this via NotifyAccess to inject arbitrary state across re-execution and obtain root privileges. Jann Horn discovered a race condition in chown_one. A local attacker could potentially exploit this by setting arbitrary permissions on certain files to obtain root privileges. This issue only affected Ubuntu 18.04 LTS and Ubuntu 18.10. It was discovered that systemd-tmpfiles mishandled symlinks in non-terminal path components. A local attacker could potentially exploit this by gaining ownership of certain files to obtain root privileges. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04 LTS. Various other issues were also addressed.

*Credits: Jann Horn
CVSS Scores
Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Attack Vector
Local
Attack Complexity
Medium
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete
* Common Vulnerability Scoring System
SSVC
  • Decision:Track*
Exploitation
None
Automatable
No
Tech. Impact
Total
* Organization's Worst-case Scenario
Timeline
  • 2018-08-22 CVE Reserved
  • 2018-10-26 CVE Published
  • 2018-10-26 First Exploit
  • 2025-03-30 EPSS Updated
  • 2025-06-09 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
CWE
  • CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Canonical
Search vendor "Canonical"
Ubuntu Linux
Search vendor "Canonical" for product "Ubuntu Linux"
16.04
Search vendor "Canonical" for product "Ubuntu Linux" and version "16.04"
lts
Affected
Canonical
Search vendor "Canonical"
Ubuntu Linux
Search vendor "Canonical" for product "Ubuntu Linux"
18.04
Search vendor "Canonical" for product "Ubuntu Linux" and version "18.04"
lts
Affected
Canonical
Search vendor "Canonical"
Ubuntu Linux
Search vendor "Canonical" for product "Ubuntu Linux"
18.10
Search vendor "Canonical" for product "Ubuntu Linux" and version "18.10"
-
Affected
Systemd Project
Search vendor "Systemd Project"
Systemd
Search vendor "Systemd Project" for product "Systemd"
>= 235 < 240
Search vendor "Systemd Project" for product "Systemd" and version " >= 235 < 240"
-
Affected