Security readout for executives and security teams
Plain-English summary
CVE-2021-3918 is a critical prototype pollution issue in kriszyp/json-schema. If software processes attacker-controlled input through this library, object behavior could be altered, risking confidentiality, integrity, and availability. The source bundle does not identify exact affected versions.
Executive priority
Prioritize remediation where the library is reachable from internet-facing or partner-facing input paths. The CVSS score is critical, but evidence is incomplete on exact affected versions and active exploitation.
Technical view
The issue is CWE-1321 prototype pollution in kriszyp/json-schema, scored CVSS 9.8 with network attack vector, low complexity, no privileges, and no user interaction. Sources reference an upstream commit and Debian LTS package update, but affected upstream versions are listed as unspecified.
Likely exposure
Exposure is most likely in Node.js applications, packages, appliances, or distributions that include kriszyp/json-schema or Debian node-json-schema. NetApp also published an advisory, so asset owners should check whether listed NetApp products apply.
Exploitation context
The bundle marks KEV as false and provides no cited evidence of active exploitation. Public vulnerability details and a fixing commit exist, so organizations should treat reachable dependency use as urgent without assuming exploitation is occurring.
Researcher notes
Key gaps are unspecified affected versions and no KEV listing. The upstream commit and Debian advisory indicate a fix path exists, but validation should rely on package metadata and vendor advisories rather than inferred version ranges.
Mitigation direction
- Inventory applications and products using kriszyp/json-schema or node-json-schema.
- Upgrade to vendor or distribution releases containing the referenced fix.
- Review Debian DLA 3228-1 if using Debian-packaged node-json-schema.
- Check the NetApp advisory for affected product-specific guidance.
- Restrict untrusted schema or JSON processing where updates are delayed.
Validation and detection
- Search SBOMs, lockfiles, and package manifests for json-schema and node-json-schema.
- Confirm deployed package versions map to vendor-fixed releases.
- Review applications for attacker-controlled data reaching json-schema processing paths.
- Check vulnerability scanners for CVE-2021-3918 findings across servers and appliances.
- For NetApp environments, compare inventory against the NetApp advisory.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-1321: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-3918 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
9.8CriticalVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://huntr.dev/bounties/bb6ccd63-f505-4e3a-b55f-cd2662c261a9CVE reference
- https://github.com/kriszyp/json-schema/commit/22f146111f541d9737e832823699ad3528ca7741CVE reference
- [debian-lts-announce] 20221206 [SECURITY] [DLA 3228-1] node-json-schema security updateCVE reference · mailing-list
- https://security.netapp.com/advisory/ntap-20250117-0004/CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.