CVE-2018-4003: An exploitable heap overflow vulnerability exists in the mdnscap binary of the CUJO Smart Firewall running fir

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2018-4003 is a critical-severity flaw (CVSS 9.8) affecting smart firewall. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An exploitable heap overflow vulnerability exists in the mdnscap binary of the CUJO Smart Firewall running firmware 7003. The string lengths are handled incorrectly when parsing character strings in mDNS resource records, leading to arbitrary code execution in the context of the mdnscap process. An unauthenticated attacker can send an mDNS message to trigger this vulnerability.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-787
Published	2019-03-21
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: getcujo

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

Am I affected?

Timeline

2019-03-21 16:29 UTCPublished CVE record published
2026-06-17 01:58 UTCUpdated Record last modified

getcujo smart firewall DOWNGRADE

Affected: 7003

Fixed in: no fixed release known

Safe to downgrade to: a release before 7003

1. Check installed version

apt-cache policy smart-firewall || rpm -q smart-firewall || smart-firewall --version

2. No fixed release: DOWNGRADE to a release before 7003 (Debian / Ubuntu)

apt-cache madison smart-firewall sudo apt install smart-firewall=<VERSION_BEFORE_7003> sudo apt-mark hold smart-firewall

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

dnf --showduplicates list smart-firewall sudo dnf downgrade smart-firewall-<VERSION_BEFORE_7003> sudo dnf versionlock add smart-firewall

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-2018-4003?

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

Is CVE-2018-4003 being exploited?

CVE-2018-4003 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-2018-4003 affect?

CVE-2018-4003 affects smart firewall. Severity is critical (CVSS 9.8). An exploitable heap overflow vulnerability exists in the mdnscap binary of the CUJO Smart Firewall running firmware 7003. The string lengths are handled incorrectly when parsing character strings in mDNS resource records, leading to arbitra

How urgent is CVE-2018-4003?

Priority 64/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2018-4031 CRITICAL 10.0 DOWNGRADE An exploitable vulnerability exists in the safe browsing function of the CUJO Smart Firewall, version 7003
CVE-2018-4030 HIGH 7.5 DOWNGRADE An exploitable vulnerability exists the safe browsing function of the CUJO Smart Firewall, version 7003
CVE-2018-4011 HIGH 7.5 DOWNGRADE An exploitable integer underflow vulnerability exists in the mdnscap binary of the CUJO Smart Firewall, versio
CVE-2018-3985 CRITICAL 9.8 DOWNGRADE An exploitable double free vulnerability exists in the mdnscap binary of the CUJO Smart Firewall
CVE-2018-3969 HIGH 7.8 DOWNGRADE An exploitable vulnerability exists in the verified boot protection of the CUJO Smart Firewall

References

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