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Fencer Vulns
high 7.5

CVE-2021-21267 json

Regular Expression Denial-of-Service in npm schema-inspector

published 2021-03-19 5 y ago modified 2026-07-08 4 mo ago also GHSA-f38p-c2gq-4pmr , EUVD-2021-0649

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

Schema-Inspector is an open-source tool to sanitize and validate JS objects (npm package schema-inspector). In before version 2.0.0, email address validation is vulnerable to a denial-of-service attack where some input (for example `a@0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.`) will freeze the program or web browser page executing the code. This affects any current schema-inspector users using any version to validate email addresses. Users who do not do email validation, and instead do other types of validation (like string min or max length, etc), are not affected. Users should upgrade to version 2.0.0, which uses a regex expression that isn't vulnerable to ReDoS.

Patch / fix

  • npm schema-inspector 2.0.0
  • schema-inspector_project schema-inspector 2.0.0

Exploit prediction

2.09% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/schema-inspector/schema-inspector/security/advisories/GHSA-f38p-c2gq-4pmr referenced PoC, tagged "exploit" by a source, unverified
  • gist.github.com https://gist.github.com/mattwelke/b7f42424680a57b8161794ad1737cd8f referenced PoC, tagged "exploit" by a source, unverified
  • npmjs.com https://www.npmjs.com/package/schema-inspector referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm schema-inspector
<2.0.0
2.0.0

Affected products

  • schema-inspector schema-inspector

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.