How severe is CVE-2021-32740?

CVE-2021-32740 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-32740?

CVE-2021-32740 affects the following packages: addressable (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2021-32740?

Update addressable to 2.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32740 is resolved across your whole dependency graph.

How do I detect CVE-2021-32740 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for addressable, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-32740 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2021-32740 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-32740 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-32740?

CVE-2021-32740 has an EPSS (Exploit Prediction Scoring System) score of 2.1%, placing it in the 82th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-32740?

CVE-2021-32740 is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-32740 published, and has it been updated?

CVE-2021-32740 was published on July 6, 2021 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

HIGH severity

CVE-2021-32740 — addressable

HIGHFix: sporkmonger/addressable@0d8a312

CVE-2021-32740 is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in addressable. A fix is available for addressable — see the affected versions and patch details below.

Regular Expression Denial of Service in Addressable templates

Also known asGHSA-jxhc-q857-3j6g

Published

Jul 6, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs82th percentile — riskier than 82% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

💎addressable

Real-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

Impact

Within the URI template implementation in Addressable, a maliciously crafted template may result in uncontrolled resource consumption, leading to denial of service when matched against a URI. In typical usage, templates would not normally be read from untrusted user input, but nonetheless, no previous security advisory for Addressable has cautioned against doing this. Users of the parsing capabilities in Addressable but not the URI template capabilities are unaffected.

Patches

The vulnerability was introduced in version 2.3.0 (previously yanked) and has been present in all subsequent versions up to, and including, 2.7.0. It is fixed in version 2.8.0.

Workarounds

The vulnerability can be avoided by only creating Template objects from trusted sources that have been validated not to produce catastrophic backtracking.

References

For more information

If you have any questions or comments about this advisory:

Open an issue

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`addressable`	≥ 2.3.0&&< 2.8.0	2.8.0`bundle update addressable --conservative`

Affected Products

2 products · 3 configurations

Application

addressableaddressable_project

≥ 2.3.0 && < 2.8.0

range

fedorafedoraproject

2 versions

3334

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for addressable, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update addressable to 2.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32740 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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.

Red HatModerate

Red Hat CloudForms 5.0 (CFME 5.11) is in the maintenance support phase and we are no longer fixing Moderate/Low severity security bugs. Reference: https://access.redhat.com/support/policy/updates/cloudforms OpenShift 3.11 components are currently in maintenance support phase, hence Moderate/Low severity security bugs…

Workaround published by Red Hat

Create template objects only from trusted sources that have been validated not to produce catastrophic backtracking.

Source: Red Hat security advisory for CVE-2021-32740 (CC BY 4.0)

Product	Fixed in	Advisory
OpenShift Logging 5.2	`openshift-logging/fluentd-rhel8:v5.2.0-10`	RHBA-2021:3393
Red Hat Satellite 6.10 for RHEL 7	`tfm-rubygem-addressable-0:2.8.0-1.el7sat`	RHSA-2021:4702

Frequently Asked Questions

### Impact Within the URI template implementation in Addressable, a maliciously crafted template may result in uncontrolled resource consumption, leading to denial of service when matched against a URI. In typical usage, templates would not normally be read from untrusted user input, but nonetheless, no previous security advisory for Addressable has cautioned against doing this. Users of the parsing capabilities in Addressable but not the URI template capabilities are unaffected. ### Patches The vulnerability was introduced in version 2.3.0 (previously yanked) and has been present in all su