CVE-2021-40660: An issue was discovered in Delight Nashorn Sandbox 0.2.0

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2021-40660 is a high-severity flaw (CVSS 7.5) affecting nashorn sandbox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-1333
Published	2022-06-14
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: javadelight

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

Am I affected?

Timeline

2022-06-14 14:15 UTCPublished CVE record published
2026-06-17 04:07 UTCUpdated Record last modified

javadelight nashorn sandbox DOWNGRADE

Affected: 0.2.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.2.0

1. Check installed version

apt-cache policy nashorn-sandbox || rpm -q nashorn-sandbox || nashorn-sandbox --version

2. No fixed release: DOWNGRADE to a release before 0.2.0 (Debian / Ubuntu)

apt-cache madison nashorn-sandbox sudo apt install nashorn-sandbox=<VERSION_BEFORE_0.2.0> sudo apt-mark hold nashorn-sandbox

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nashorn-sandbox sudo dnf downgrade nashorn-sandbox-<VERSION_BEFORE_0.2.0> sudo dnf versionlock add nashorn-sandbox

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-2021-40660?

nashorn sandbox: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-40660 being exploited?

CVE-2021-40660 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-2021-40660 affect?

CVE-2021-40660 affects nashorn sandbox. Severity is high (CVSS 7.5). 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.

How urgent is CVE-2021-40660?

Priority 52/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-26919 HIGH 7.2 DOWNGRADE delight-nashorn-sandbox 0.2.4 and 0.2.5 is vulnerable to sandbox escape

References

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