CVE-2018-5739 | Failure to release memory may exhaust system resources

An extension to hooks capabilities which debuted in Kea 1.4.0 introduced a memory leak for operators who are using certain hooks library facilities. In order to support multiple requests simultaneously, Kea 1.4 added a callout handle store but unfortunately the initial implementation of this store does not properly free memory in every case. Hooks which make use of query4 or query6 parameters in their callouts can leak memory, resulting in the eventual exhaustion of available memory and subsequent failure of the server process. Affects Kea DHCP 1.4.0.

Published: 2019-01-16 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-5739 is rated Moderate Risk (55.6/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.97%). Review affected assets and schedule remediation.

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-2018-5739

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 2026-06-15 3.27% 2.97% -0.30%
2 2025-03-30 5.02% 3.27% -1.75%
3 2025-03-29 — 5.02% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-5739

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.0 MEDIUM
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
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:N)
No account or special rights needed—anonymous or random user is enough.
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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 3.6 [email protected]
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:N)
No account or special rights needed—anonymous or random user is enough.
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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2018-5739

OS Trackers for CVE-2018-5739

vendor priority summary link
debian unimportant CVE-2018-5739 unimportant priority: Debian including 1 source packages (isc-kea), 4 status rows across 4 suites (bookworm, forky, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2018-5739
ubuntu medium CVE-2018-5739 medium priority: Ubuntu including 1 source packages (isc-kea), 15 status rows across 15 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, trusty, upstream, xenial): ignored 7, not-affected 7, DNE 1. https://ubuntu.com/security/CVE-2018-5739

Affected software / configurations for CVE-2018-5739

Vendor Product Version Raw CPE
isc kea 1.4.0 cpe:2.3:a:isc:kea:1.4.0:*:*:*:*:*:*:*

References for CVE-2018-5739

URL Tags
https://kb.isc.org/docs/aa-01626 Vendor Advisory
cvelogic Threat Intelligence