CVE-2022-28738: A double free was found in the Regexp compiler in Ruby 3.x before 3.0.4 and 3.1.x before 3.1.2

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CRITICAL 9.8REMOTEUPGRADE

CVE-2022-28738 is a critical-severity flaw (CVSS 9.8) affecting ruby. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A double free was found in the Regexp compiler in Ruby 3.x before 3.0.4 and 3.1.x before 3.1.2. If a victim attempts to create a Regexp from untrusted user input, an attacker may be able to write to unexpected memory locations.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.1% (top 12%)
CISA exploited list	No
Weakness	CWE-415
Published	2022-05-09
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: ruby-lang

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

Am I affected?

Timeline

2022-05-09 18:15 UTCPublished CVE record published
2026-06-17 04:38 UTCUpdated Record last modified

ruby-lang ruby UPGRADE

Affected: >= 3.0.0 and < 3.0.4 · >= 3.1.0 and < 3.1.2

Fixed in: 3.0.4, 3.1.2

Safe to downgrade to: a release before 3.0.0

1. Check installed version

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

2. UPGRADE to 3.0.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ruby

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 3.0.0 (Debian / Ubuntu)

apt-cache madison ruby sudo apt install ruby=<VERSION_BEFORE_3.0.0> sudo apt-mark hold ruby

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

dnf --showduplicates list ruby sudo dnf downgrade ruby-<VERSION_BEFORE_3.0.0> sudo dnf versionlock add ruby

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.

Advisories and coverage

Official advisories

Ruby News: Regexp compilation fixes related to GitLab's CVE-2026-89078, CVE-2026-93577, CVE-2026-97229 and CVE-2026-110264 2026-10-23

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-2022-28738?

ruby: upgrade to 3.0.4, 3.1.2. Exact commands for each OS are on this page.

Is CVE-2022-28738 being exploited?

CVE-2022-28738 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-2022-28738 affect?

CVE-2022-28738 affects ruby. Severity is critical (CVSS 9.8). A double free was found in the Regexp compiler in Ruby 3.x before 3.0.4 and 3.1.x before 3.1.2. If a victim attempts to create a Regexp from untrusted user input, an attacker may be able to write to unexpected memory locations.

How urgent is CVE-2022-28738?

Priority 61/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

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References

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