CVE-2026-33176: Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework

This month

HIGH 7.5REMOTEUPGRADE

CVE-2026-33176 is a high-severity flaw (CVSS 7.5) affecting rails. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, Active Support number helpers accept strings containing scientific notation (e.g. `1e10000`), which `BigDecimal` expands into extremely large decimal representations. This can cause excessive memory allocation and CPU consumption when the expanded number is formatted, possibly resulting in

Why this priority

High severity
Remotely exploitable, no login, no user action

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	0.9% (top 42%)
CISA exploited list	No
Weakness	CWE-400, CWE-770
Published	2026-03-24
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: rubyonrails

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

Am I affected?

Timeline

2026-03-24 00:16 UTCPublished CVE record published
2026-06-17 10:37 UTCUpdated Record last modified

rubyonrails rails UPGRADE

Affected: < 7.2.3.1 · >= 8.0.0 and < 8.0.4.1 · >= 8.1.0 and < 8.1.2.1

Fixed in: 7.2.3.1, 8.0.4.1, 8.1.2.1

Safe to downgrade to: a release before 8.0.0

1. Check installed version

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

2. UPGRADE to 7.2.3.1 (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 8.0.0 (Debian / Ubuntu)

apt-cache madison rails sudo apt install rails=<VERSION_BEFORE_8.0.0> 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_8.0.0> 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.

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-2026-33176?

rails: upgrade to 7.2.3.1, 8.0.4.1, 8.1.2.1. Exact commands for each OS are on this page.

Is CVE-2026-33176 being exploited?

CVE-2026-33176 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-2026-33176 affect?

CVE-2026-33176 affects rails. Severity is high (CVSS 7.5). Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, Active Support number helpers accept strings containing scientific notation (e.g.

How urgent is CVE-2026-33176?

Priority 46/100. High severity; Remotely exploitable, no login, no user action

Software pages

Ruby on Rails vulnerabilities · Ruby vulnerabilities

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References

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