CVE-2023-22795: A regular expression based DoS vulnerability in Action Dispatch <6.1.7.1 and <7.0.4.1 related to the If-None-M

Q: How do I fix CVE-2023-22795?

rails: upgrade to 6.1.7.1, 7.0.4.1; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2023-22795 being exploited?

CVE-2023-22795 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2023-22795 affect?

CVE-2023-22795 affects rails, debian linux. Severity is high (CVSS 7.5). A regular expression based DoS vulnerability in Action Dispatch <6.1.7.1 and <7.0.4.1 related to the If-None-Match header. A specially crafted HTTP If-None-Match header can cause the regular expression engine to enter a state of catastrophi

Q: How urgent is CVE-2023-22795?

Priority 57/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2023-22795 is a high-severity flaw (CVSS 7.5) affecting rails, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A regular expression based DoS vulnerability in Action Dispatch <6.1.7.1 and <7.0.4.1 related to the If-None-Match header. A specially crafted HTTP If-None-Match header can cause the regular expression engine to enter a state of catastrophic backtracking, when on a version of Ruby below 3.2.0. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability All users running an affected release should eit

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

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	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-400, CWE-1333
Published	2023-02-09
Last modified	2026-10-24

Publisher (CNA): HackerOne · Vendor: debian · rubyonrails

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-02-09 20:15 UTCPublished CVE record published
2026-10-24 13:10 UTCUpdated Record last modified

rubyonrails rails UPGRADE

Affected: < 6.1.7.1 · >= 7.0.0 and < 7.0.4.1

Fixed in: 6.1.7.1, 7.0.4.1

Safe to downgrade to: a release before 7.0.0

1. Check installed version

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

2. UPGRADE to 6.1.7.1 (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 7.0.0 (Debian / Ubuntu)

apt-cache madison rails sudo apt install rails=<VERSION_BEFORE_7.0.0> 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_7.0.0> 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: 11.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 11.0

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

RubyGems · actionpack · FIXED · 7.0.4.1 · vulnerable: >= 7.0.0, < 7.0.4.1 · source

bundle update actionpack bundle list | grep actionpack

Fedora 46 · gnome-shell-extension-tiling-assistant · FIXED · 56-1.fc46 · FEDORA-2026-ebf66a5321 · source

sudo dnf upgrade --advisory=FEDORA-2026-ebf66a5321

Debian 12 · rails · FIXED · 2:6.1.7.3+dfsg-1

sudo apt update && sudo apt install --only-upgrade rails dpkg --compare-versions "$(dpkg-query -W -f='${Version}' rails)" ge "2:6.1.7.3+dfsg-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · rails · FIXED · 2:6.1.7.3+dfsg-1

sudo apt update && sudo apt install --only-upgrade rails dpkg --compare-versions "$(dpkg-query -W -f='${Version}' rails)" ge "2:6.1.7.3+dfsg-1" && echo PATCHED || echo STILL-VULNERABLE

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-2023-22795?

rails: upgrade to 6.1.7.1, 7.0.4.1; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-22795 being exploited?

CVE-2023-22795 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-2023-22795 affect?

CVE-2023-22795 affects rails, debian linux. Severity is high (CVSS 7.5). A regular expression based DoS vulnerability in Action Dispatch <6.1.7.1 and <7.0.4.1 related to the If-None-Match header. A specially crafted HTTP If-None-Match header can cause the regular expression engine to enter a state of catastrophi

How urgent is CVE-2023-22795?

Priority 57/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Ruby on Rails vulnerabilities · Debian vulnerabilities · Ruby vulnerabilities

Related CVEs

CVE-2023-22792 HIGH 7.5 UPGRADE A regular expression based DoS vulnerability in Action Dispatch <6.0.6.1,< 6.1.7.1, and <7.0.4.1

References

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