CVE-2018-5739: An extension to hooks capabilities which debuted in Kea 1.4.0 introduced a memory leak for operators who are u

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MEDIUM 6.5DOWNGRADE

CVE-2018-5739 is a medium-severity flaw (CVSS 6.5) affecting kea. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 ev

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.9% (top 20%)
CISA exploited list	No
Weakness	CWE-772
Published	2019-01-16
Last modified	2026-06-17

Publisher (CNA): Internet Systems Consortium (ISC) · Vendor: isc

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

Am I affected?

Timeline

2019-01-16 20:29 UTCPublished CVE record published
2026-06-17 02:00 UTCUpdated Record last modified

isc kea DOWNGRADE

Affected: 1.4.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.4.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.4.0 (Debian / Ubuntu)

apt-cache madison kea sudo apt install kea=<VERSION_BEFORE_1.4.0> sudo apt-mark hold kea

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list kea sudo dnf downgrade kea-<VERSION_BEFORE_1.4.0> sudo dnf versionlock add kea

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2018-5739?

kea: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-5739 being exploited?

CVE-2018-5739 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-2018-5739 affect?

CVE-2018-5739 affects kea. Severity is medium (CVSS 6.5). 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

How urgent is CVE-2018-5739?

Priority 43/100. No elevated risk signals yet.

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References

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