CVE-2021-23420: This affects the package codeception/codeception from 4.0.0 and before 4.1.22, before 3.1.3

This week

HIGH 7.7REMOTEUPGRADE

CVE-2021-23420 is a high-severity flaw (CVSS 7.7) affecting codeception. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

This affects the package codeception/codeception from 4.0.0 and before 4.1.22, before 3.1.3. The RunProcess class can be leveraged as a gadget to run arbitrary commands on a system that is deserializing user input without validation.

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	7.7 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	2.7% (top 14%)
CISA exploited list	No
Weakness	CWE-502
Published	2021-08-11
Last modified	2026-06-17

Publisher (CNA): Snyk · Vendor: codeception

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

Am I affected?

Timeline

2021-08-11 13:15 UTCPublished CVE record published
2026-06-17 03:38 UTCUpdated Record last modified

codeception codeception UPGRADE

Affected: < 3.1.3 · >= 4.0.0 and < 4.1.22

Fixed in: 3.1.3, 4.1.22

Safe to downgrade to: a release before 4.0.0

1. Check installed version

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

2. UPGRADE to 3.1.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade codeception

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 4.0.0 (Debian / Ubuntu)

apt-cache madison codeception sudo apt install codeception=<VERSION_BEFORE_4.0.0> sudo apt-mark hold codeception

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

dnf --showduplicates list codeception sudo dnf downgrade codeception-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add codeception

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-2021-23420?

codeception: upgrade to 3.1.3, 4.1.22. Exact commands for each OS are on this page.

Is CVE-2021-23420 being exploited?

CVE-2021-23420 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-2021-23420 affect?

CVE-2021-23420 affects codeception. Severity is high (CVSS 7.7). This affects the package codeception/codeception from 4.0.0 and before 4.1.22, before 3.1.3. The RunProcess class can be leveraged as a gadget to run arbitrary commands on a system that is deserializing user input without validation.

How urgent is CVE-2021-23420?

Priority 58/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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