CVE-2021-36213: HashiCorp Consul and Consul Enterprise 1.9.0 through 1.10.0 default deny policy with a single L7 application-a

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HIGH 7.5REMOTEUPGRADE

CVE-2021-36213 is a high-severity flaw (CVSS 7.5) affecting consul. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

HashiCorp Consul and Consul Enterprise 1.9.0 through 1.10.0 default deny policy with a single L7 application-aware intention deny action cancels out, causing the intention to incorrectly fail open, allowing L4 traffic. Fixed in 1.9.8 and 1.10.1.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.7% (top 23%)
CISA exploited list	No
Published	2021-07-17
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

2021-07-17 18:15 UTCPublished CVE record published
2026-06-17 03:58 UTCUpdated Record last modified

hashicorp consul UPGRADE

Affected: >= 1.9.0 and < 1.9.8 · >= 1.10.0 and < 1.10.1

Fixed in: 1.9.8, 1.10.1

Safe to downgrade to: a release before 1.9.0

1. Check installed version

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

2. UPGRADE to 1.9.8 (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 1.9.0 (Debian / Ubuntu)

apt-cache madison consul sudo apt install consul=<VERSION_BEFORE_1.9.0> 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_1.9.0> 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-2021-36213?

consul: upgrade to 1.9.8, 1.10.1. Exact commands for each OS are on this page.

Is CVE-2021-36213 being exploited?

CVE-2021-36213 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-2021-36213 affect?

CVE-2021-36213 affects consul. Severity is high (CVSS 7.5). HashiCorp Consul and Consul Enterprise 1.9.0 through 1.10.0 default deny policy with a single L7 application-aware intention deny action cancels out, causing the intention to incorrectly fail open, allowing L4 traffic. Fixed in 1.9.8 and 1.

How urgent is CVE-2021-36213?

Priority 50/100. High severity; Remotely exploitable, no login, no user action

Software pages

Consul vulnerabilities

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References

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