What’s Vulnerable › Vulnerabilities

CVE-2021-3918: Prototype Pollution in kriszyp/json-schema

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.8% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-11-13 · updated 2026-06-17
• Weakness: CWE-1321

Description

json-schema is vulnerable to Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Affected products

• Debian Linux: 10.0
• Json-Schema Project Json-Schema: before 0.4.0 — fixed in 0.4.0
• Npm Json-Schema: before 0.4.0 — fixed in 0.4.0

How to fix

Upgrade to a fixed version: Json-Schema Project Json-Schema 0.4.0; Npm Json-Schema 0.4.0. Check the vendor advisory for mitigations.

References

• https://github.com/kriszyp/json-schema/commit/22f146111f541d9737e832823699ad3528ca7741
• https://huntr.dev/bounties/bb6ccd63-f505-4e3a-b55f-cd2662c261a9
• https://lists.debian.org/debian-lts-announce/2022/12/msg00013.html
• https://github.com/kriszyp/json-schema/commit/22f146111f541d9737e832823699ad3528ca7741
• https://huntr.dev/bounties/bb6ccd63-f505-4e3a-b55f-cd2662c261a9
• https://lists.debian.org/debian-lts-announce/2022/12/msg00013.html
• https://security.netapp.com/advisory/ntap-20250117-0004/

Get alerted when CVE-2021-3918 or the next vulnerability affects your stack