CVE-2023-22796 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in activesupport. A fix is available for activesupport — see the affected versions and patch details below.
ReDoS based DoS vulnerability in Active Support's underscore
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-22796.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-22796 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
activesupport💎activesupportReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
There is a possible regular expression based DoS vulnerability in Active Support. This vulnerability has been assigned the CVE identifier CVE-2023-22796.
Versions Affected: All Not affected: None Fixed Versions: 5.2.8.15 (Rails LTS, which is a paid service and not part of the rubygem), 6.1.7.1, 7.0.4.1 Impact
A specially crafted string passed to the underscore method can cause the regular expression engine to enter a state of catastrophic backtracking. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability.
This affects String#underscore, ActiveSupport::Inflector.underscore, String#titleize, and any other methods using these.
All users running an affected release should either upgrade or use one of the workarounds immediately. Releases
The FIXED releases are available at the normal locations. Workarounds
There are no feasible workarounds for this issue.
Users on Ruby 3.2.0 or greater may be able to reduce the impact by configuring Regexp.timeout. Patches
To aid users who aren’t able to upgrade immediately we have provided patches for the two supported release series. They are in git-am format and consist of a single changeset.
6-1-Avoid-regex-backtracking-in-Inflector.underscore.patch - Patch for 6.1 series
7-0-Avoid-regex-backtracking-in-Inflector.underscore.patch - Patch for 7.0 series
Please note that only the 7.0.Z and 6.1.Z series are supported at present, and 6.0.Z for severe vulnerabilities. Users of earlier unsupported releases are advised to upgrade as soon as possible as we cannot guarantee the continued availability of security fixes for unsupported releases.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | activesupport | all versions | 6.1.7.1bundle update activesupport --conservative |
| 💎RubyGems | activesupport | ≥ 7.0.0&&< 7.0.4.1 | 7.0.4.1bundle update activesupport --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for activesupport, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update activesupport to 6.1.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-22796 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-22796 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-22796. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Satellite 6.14 for RHEL 8 | rubygem-activesupport-0:6.1.7.3-1.el8sat | RHSA-2023:6818 |
| RHOL-5.7-RHEL-8 | openshift-logging/fluentd-rhel8:v1.14.6-152 | RHSA-2023:4341 |
Frequently Asked Questions
Is CVE-2023-22796 in your dependencies?
O3 Security finds CVE-2023-22796 across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.