CVE-2018-9336: openvpnserv.exe (aka the interactive service helper) in OpenVPN 2.4.x before 2.4.6 allows a local attacker to

This month

HIGH 7.8WATCHLISTUPGRADEMITIGATE

CVE-2018-9336 is a high-severity flaw (CVSS 7.8) affecting openvpn, slackware linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

openvpnserv.exe (aka the interactive service helper) in OpenVPN 2.4.x before 2.4.6 allows a local attacker to cause a double-free of memory by sending a malformed request to the interactive service. This could cause a denial-of-service through memory corruption or possibly have unspecified other impact including privilege escalation.

Why this priority

High severity
Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-415
Published	2018-05-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: openvpn · slackware

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

Am I affected?

Timeline

2018-05-01 18:29 UTCPublished CVE record published
2026-06-17 02:06 UTCUpdated Record last modified

openvpn openvpn UPGRADE

Affected: >= 2.4.0 and < 2.4.6

Fixed in: 2.4.6

Safe to downgrade to: a release before 2.4.0

1. Check installed version

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

2. UPGRADE to 2.4.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openvpn

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openvpn

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.4.0 (Debian / Ubuntu)

apt-cache madison openvpn sudo apt install openvpn=<VERSION_BEFORE_2.4.0> sudo apt-mark hold openvpn

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list openvpn sudo dnf downgrade openvpn-<VERSION_BEFORE_2.4.0> sudo dnf versionlock add openvpn

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.

slackware slackware linux MITIGATE

Affected: 13.0 · 13.1 · 13.37 · 14.0 · 14.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 13.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2018-9336?

openvpn: upgrade to 2.4.6; slackware linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-9336 being exploited?

CVE-2018-9336 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-2018-9336 affect?

CVE-2018-9336 affects openvpn, slackware linux. Severity is high (CVSS 7.8). openvpnserv.exe (aka the interactive service helper) in OpenVPN 2.4.x before 2.4.6 allows a local attacker to cause a double-free of memory by sending a malformed request to the interactive service. This could cause a denial-of-service thro

How urgent is CVE-2018-9336?

Priority 49/100. High severity; Public exploit reference; On your watchlist

Software pages

OpenVPN vulnerabilities

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References

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