LiveActive security incident?Get immediate response
CVE Record

CVE-2021-23470: Prototype Pollution

This affects the package putil-merge before 3.8.0. The merge() function does not check the values passed into the argument. An attacker can supply a malicious value by adjusting the value to include the constructor property. Note: This vulnerability derives from an incomplete fix in https://security.snyk.io/vuln/SNYK-JS-PUTILMERGE-1317077

HighCVSS 8.2Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-23470 is a high-severity prototype pollution issue in the npm package putil-merge before 3.8.0. If an application merges attacker-controlled objects, the attacker may influence shared JavaScript object behavior, potentially disrupting service or changing application logic.

Executive priority

Prioritize remediation for internet-facing services or systems processing external JSON-like input. Where exposure is only internal and merge() does not receive untrusted data, handle through the normal high-severity dependency patch cycle.

Technical view

The putil-merge merge() function did not adequately check values containing the constructor property. This incomplete fix of an earlier issue can allow prototype pollution when malicious input reaches merge(). CVSS 3.1 is 8.2, with network attack vector, no privileges, no user interaction, low integrity impact, and high availability impact.

Likely exposure

Exposure is likely in Node.js applications that directly or transitively depend on putil-merge before 3.8.0 and pass untrusted data into merge(). The sources do not identify specific downstream products or platforms.

Exploitation context

The source bundle lists proof-of-concept exploit maturity in the CVSS vector, but CISA KEV is false and no cited source establishes active exploitation. Treat this as credible but not confirmed exploited in the wild.

Researcher notes

Evidence is limited to the CVE description, Snyk advisory reference, and upstream commit reference. The bundle does not provide affected application examples, public exploitation evidence, or detailed exploitation prerequisites beyond malicious constructor-property input reaching merge().

Mitigation direction

  • Upgrade putil-merge to version 3.8.0 or later.
  • Pin or override transitive dependencies that resolve to vulnerable putil-merge versions.
  • Avoid passing untrusted request, configuration, or JSON data directly into merge().
  • Monitor the Snyk advisory and upstream repository for additional vendor guidance.

Validation and detection

  • Check package manifests, lockfiles, and SBOMs for putil-merge before 3.8.0.
  • Identify whether putil-merge is direct or transitive in deployed applications.
  • Review call paths where merge() receives user-controlled or external object data.
  • Run dependency and regression tests after upgrading or overriding the package.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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.

cve · low confidence lookup

CVE-2021-23470 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
8.2 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H/E:P

Official CVE source material

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.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
8.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H/E:P3.94.2Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

8.2High
CVSS 3.1 vector shape for CVE-2021-23470Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H/E:P

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/aputil-mergeunspecifiedListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.