VulnerabilityPublished 21 Jan 2020Updated 9 Jun 2025

CVE-2019-20386: systemd · Memory Leak

Source CVE Database V5

Not known to be exploited · CVSS 5.1 Medium : upgrade to 243 when convenient.

Data as of 26 Oct 2026, 11:07 UTC

CVSS 3.1 base score

5.1Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 243

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Jan 2020
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade systemd/systemd to 243.

Affected software

Product	Affected	Fixed in
GitHubsystemd/systemd`pkg:github/systemd/systemd`Other threats	Affected <243	Fixed in 243

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2019-20386, European organizations should: 1) Identify all Linux systems running systemd versions earlier than 243 by inventorying installed packages and versions. 2) Apply updates and patches from their Linux distribution vendors that include systemd version 243 or later, as these contain fixes for the memory leak. 3) If immediate patching is not possible, monitor system memory usage closely on affected systems, especially those running 'udevadm trigger' commands or similar operations that could trigger the leak. 4) Limit the use of 'udevadm trigger' to trusted administrators and scripts to reduce unnecessary triggering of the vulnerable code path. 5) Implement system resource monitoring and alerting to detect abnormal memory consumption trends that could indicate exploitation or impact from the leak. 6) Follow best practices for system hardening and minimize local access to reduce the risk of exploitation by unauthorized users. 7) Engage with Linux distribution security advisories and subscribe to vulnerability notifications to stay informed about patches and related issues.

Description

An issue was discovered in button_open in login/logind-button.c in systemd before 243. When executing the udevadm trigger command, a memory leak may occur.

Impact

For European organizations, the impact of CVE-2019-20386 depends largely on their use of Linux systems running systemd versions prior to 243. Since systemd is the default init system for most modern Linux distributions, including Debian, Ubuntu, Fedora, and others widely used in Europe, the vulnerability could affect a broad range of servers and workstations. The memory leak could lead to gradual resource depletion, potentially causing degraded performance or system instability over time, especially on systems with limited memory or those running critical services continuously. While it does not directly allow for remote code execution or privilege escalation, the indirect effects could disrupt business operations if not addressed. Organizations relying on Linux for critical infrastructure, cloud services, or internal systems could face increased maintenance overhead and risk of service degradation. However, the lack of known exploits and the medium CVSS score indicate that the immediate threat level is moderate, but patching remains important to maintain system reliability and security hygiene.

CWE-401Missing Release of Memory after Effective Lifetime (opens in a new tab)
Variant weaknessLikelihood of exploit: Medium
The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
Implementation · Libraries or Frameworks
Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Architecture and Design · Build and Compilation
Consider using the Boehm-Demers-Weiser garbage collector (bdwgc), which can help avoid leaks.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Jul 2025, 21:04 UTC

WeaknessesCWE-401

Technical details

References

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