CVE-2018-19653: HashiCorp Consul 0.5.1 through 1.4.0 can use cleartext agent-to-agent RPC communication because the verify_out

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MEDIUM 5.9REMOTEUPGRADE

CVE-2018-19653 is a medium-severity flaw (CVSS 5.9) affecting consul. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

HashiCorp Consul 0.5.1 through 1.4.0 can use cleartext agent-to-agent RPC communication because the verify_outgoing setting is improperly documented. NOTE: the vendor has provided reconfiguration steps that do not require a software upgrade.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 31%)
CISA exploited list	No
Weakness	CWE-310
Published	2018-12-09
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: hashicorp

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

Am I affected?

Timeline

2018-12-09 19:29 UTCPublished CVE record published
2026-06-17 01:49 UTCUpdated Record last modified

hashicorp consul UPGRADE

Affected: >= 0.5.1 and <= 1.4.0

Fixed in: newer than 1.4.0

Safe to downgrade to: a release before 0.5.1

1. Check installed version

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

2. UPGRADE to newer than 1.4.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade consul

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 0.5.1 (Debian / Ubuntu)

apt-cache madison consul sudo apt install consul=<VERSION_BEFORE_0.5.1> sudo apt-mark hold consul

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

dnf --showduplicates list consul sudo dnf downgrade consul-<VERSION_BEFORE_0.5.1> sudo dnf versionlock add consul

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-2018-19653?

consul: upgrade to newer than 1.4.0. Exact commands for each OS are on this page.

Is CVE-2018-19653 being exploited?

CVE-2018-19653 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-2018-19653 affect?

CVE-2018-19653 affects consul. Severity is medium (CVSS 5.9). HashiCorp Consul 0.5.1 through 1.4.0 can use cleartext agent-to-agent RPC communication because the verify_outgoing setting is improperly documented. NOTE: the vendor has provided reconfiguration steps that do not require a software upgrade

How urgent is CVE-2018-19653?

Priority 43/100. Remotely exploitable, no login, no user action

Software pages

Consul vulnerabilities

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References

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