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CVE-2022-23634: Puma is a Ruby/Rack web server built for parallelism

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This month
HIGH 8.0WATCHLISTUPGRADEUPGRADEMITIGATE

CVE-2022-23634 is a high-severity flaw (CVSS 8.0) affecting puma, rails, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Puma is a Ruby/Rack web server built for parallelism. Prior to `puma` version `5.6.2`, `puma` may not always call `close` on the response body. Rails, prior to version `7.0.2.2`, depended on the response body being closed in order for its `CurrentAttributes` implementation to work correctly. The combination of these two behaviors (Puma not closing the body + Rails' Executor implementation) causes information leakage. This problem is fixed in Puma

Why this priority

  • High severity
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score8.0 (High)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededNone
User interactionRequired
EPSS exploit chance2.1% (top 18%)
CISA exploited listNo
WeaknessCWE-200, CWE-404
Published2022-02-11
Last modified2026-06-17
Publisher (CNA): GitHub, Inc. · Vendor: debian · fedoraproject · puma · rubyonrails

Share: LinkedIn · X · Reddit

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

Am I affected?

Timeline

puma puma UPGRADE
Affected: < 4.3.11 · >= 5.0.0 and < 5.6.2
Fixed in: 4.3.11, 5.6.2
Safe to downgrade to: a release before 5.0.0
1. Check installed version
apt-cache policy puma || rpm -q puma || puma --version
2. UPGRADE to 4.3.11 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade puma
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade puma
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 5.0.0 (Debian / Ubuntu)
apt-cache madison puma sudo apt install puma=<VERSION_BEFORE_5.0.0> sudo apt-mark hold puma
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list puma sudo dnf downgrade puma-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add puma
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.
rubyonrails rails UPGRADE
Affected: >= 5.0.0 and < 5.2.6.2 · >= 6.0.0 and < 6.0.4.6 · >= 6.1.0 and < 6.1.4.6 · >= 7.0.0 and < 7.0.2.2
Fixed in: 5.2.6.2, 6.0.4.6, 6.1.4.6, 7.0.2.2
Safe to downgrade to: a release before 5.0.0
1. Check installed version
apt-cache policy rails || rpm -q rails || rails --version
2. UPGRADE to 5.2.6.2 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade rails
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade rails
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 5.0.0 (Debian / Ubuntu)
apt-cache madison rails sudo apt install rails=<VERSION_BEFORE_5.0.0> sudo apt-mark hold rails
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list rails sudo dnf downgrade rails-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add rails
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.
debian debian linux MITIGATE
Affected: 9.0 · 10.0 · 11.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 9.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
fedoraproject fedora MITIGATE
Affected: 35 · 36 · 37
Fixed in: no fixed release known
Safe to downgrade to: a release before 35
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
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-2022-23634?

puma: upgrade to 4.3.11, 5.6.2; rails: upgrade to 5.2.6.2, 6.0.4.6, 6.1.4.6, 7.0.2.2; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2022-23634 being exploited?

CVE-2022-23634 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-2022-23634 affect?

CVE-2022-23634 affects puma, rails, debian linux. Severity is high (CVSS 8.0). Puma is a Ruby/Rack web server built for parallelism. Prior to `puma` version `5.6.2`, `puma` may not always call `close` on the response body. Rails, prior to version `7.0.2.2`, depended on the response body being closed in order for its `

How urgent is CVE-2022-23634?

Priority 53/100. High severity; On your watchlist

Software pages

Ruby on Rails vulnerabilities · Debian vulnerabilities · Ruby vulnerabilities

Related CVEs

References

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