CVE-2021-40901: A Regular Expression Denial of Service (ReDOS) vulnerability was discovered in scniro-validator v1.0.1 when va

Q: How do I fix CVE-2021-40901?

scniro-validator: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-40901 being exploited?

CVE-2021-40901 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-40901 affect?

CVE-2021-40901 affects scniro-validator. Severity is high (CVSS 7.5). A Regular Expression Denial of Service (ReDOS) vulnerability was discovered in scniro-validator v1.0.1 when validating crafted invalid emails.

Q: How urgent is CVE-2021-40901?

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

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2021-40901 is a high-severity flaw (CVSS 7.5) affecting scniro-validator. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A Regular Expression Denial of Service (ReDOS) vulnerability was discovered in scniro-validator v1.0.1 when validating crafted invalid emails.

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	1.1% (top 36%)
CISA exploited list	No
Weakness	CWE-1333
Published	2022-06-27
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: scniro-validator project

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

Am I affected?

Timeline

2022-06-27 13:15 UTCPublished CVE record published
2026-06-17 04:07 UTCUpdated Record last modified

scniro-validator project scniro-validator DOWNGRADE

Affected: 1.0.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0.1

1. Check installed version

npm ls scniro-validator

2. No fixed release: DOWNGRADE to a release before 1.0.1

npm view scniro-validator versions npm install scniro-validator@"<1.0.1"

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-2021-40901?

scniro-validator: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-40901 being exploited?

CVE-2021-40901 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-2021-40901 affect?

CVE-2021-40901 affects scniro-validator. Severity is high (CVSS 7.5). A Regular Expression Denial of Service (ReDOS) vulnerability was discovered in scniro-validator v1.0.1 when validating crafted invalid emails.

How urgent is CVE-2021-40901?

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

References

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