How severe is CVE-2021-40660?

CVE-2021-40660 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-40660?

CVE-2021-40660 affects the following packages: org.javadelight:delight-nashorn-sandbox (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-40660?

Update org.javadelight:delight-nashorn-sandbox to 0.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-40660 is resolved across your whole dependency graph.

How do I detect CVE-2021-40660 in my Maven dependencies?

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

How do I mitigate CVE-2021-40660 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-2021-40660 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-40660, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-40660?

CVE-2021-40660 has an EPSS (Exploit Prediction Scoring System) score of 1.0%, placing it in the 64th 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-2021-40660?

CVE-2021-40660 is classified as CWE-1333 (CWE-1333). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-40660 published, and has it been updated?

CVE-2021-40660 was published on June 14, 2022 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.

☕

☕ Maven

Not in CISA KEV

HIGH severity

CVE-2021-40660 — delight-nashorn-sandbox

HIGHFix: javadelight/delight-nashorn-sandbox#139

CVE-2021-40660 is a high-severity (CVSS 7.5) CWE-1333 vulnerability in org.javadelight:delight-nashorn-sandbox. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.javadelight:delight-nashorn-sandbox — see the affected versions and patch details below.

Regular expression denial of service in Delight Nashorn Sandbox

Also known asGHSA-38j3-6fm8-pfgc

Published

Jun 14, 2022

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.0%probability of exploitation in next 30 days

Lower Risk+0.02%

Lower risk than most CVEs64th percentile — riskier than 64% 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

☕org.javadelight:delight-nashorn-sandbox

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

An issue was discovered in Delight Nashorn Sandbox 0.2.0. There is an ReDoS vulnerability that can be exploited to launching a denial of service (DoS) attack.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.javadelight:delight-nashorn-sandbox`	all versions	0.3.1`org.javadelight:delight-nashorn-sandbox:0.3.1`

Affected Products

1 product · 1 configurations

Application

nashorn sandboxjavadelight

1 version

0.2.0

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

An issue was discovered in Delight Nashorn Sandbox 0.2.0. There is an Re…

github.comNVDJun 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.javadelight:delight-nashorn-sandbox, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.javadelight:delight-nashorn-sandbox to 0.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-40660 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.

Frequently Asked Questions

An issue was discovered in Delight Nashorn Sandbox 0.2.0. There is an ReDoS vulnerability that can be exploited to launching a denial of service (DoS) attack.

O3 Security · Impact-Aware SCA

Is CVE-2021-40660 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE Classification

CWE-1333CWE-1333

Weaponization

No Nuclei template or Metasploit module yet. 1 public proof-of-concept reference is listed on this page.

OpenSSF Scorecard

Package health score

delight-nashorn-sandbox

3.2/10

Maintained0/10

Code-Review0/10

Branch-Protection0/10

Assessed Nov 9, 2026

Timeline

Disclosed

Jun 14, 2022

First exploit

Jun 22, 2022

Last updated

Oct 20, 2026

Identifiers

CVE-2021-40660

GHSA-38j3-6fm8-pfgc

References

Advisorynvd.nist.gov · CVE 2021 40660 Reportgithub.com Webgithub.com Webgithub.com Webgithub.com · b899b8ecad46090fdc042ac7683e1164114a69de Webgithub.com · 0.3.1 Packagegithub.com · delight nashorn sandbox

Related vulnerabilities

This CVE is high severity; 6 of 8 other CVEs with CWE-1333 are rated as high or higher (top: high).

CVE-2026-125333CVE-2026-118772CVE-2026-118779CVE-2026-119202CVE-2026-118259CVE-2026-116795CVE-2026-115887CVE-2026-116588Browse all CWE-1333

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026

CVE-2021-40660 — delight-nashorn-sandbox

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2021-40660 in your dependencies?