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CVE Record

CVE-2021-23421: Prototype Pollution

All versions of package merge-change are vulnerable to Prototype Pollution via the utils.set function.

MediumCVSS 5.6Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-23421 is a prototype pollution issue in the JavaScript package merge-change. If an application lets untrusted data reach the vulnerable utils.set behavior, an attacker may be able to alter shared object behavior and cause limited confidentiality, integrity, or availability impact.

Executive priority

Treat this as a moderate dependency risk. It does not have known active exploitation in the provided sources, but it can affect application trust boundaries where user-controlled structured data is processed.

Technical view

The source bundle states all versions of merge-change are vulnerable through utils.set. The CVSS 3.1 score is 5.6 with network attack vector, high complexity, no privileges, and no user interaction. Exploit maturity is unproven and CISA KEV is false.

Likely exposure

Exposure is limited to applications that install merge-change and pass attacker-controlled data into the affected utility path. Risk is lower where the package is absent, unused, or only processes trusted internal data.

Exploitation context

No cited source in the bundle reports active exploitation, and the CVSS vector marks exploit code maturity as unproven. The vulnerability is remotely reachable only when application data flow exposes the affected package behavior to untrusted input.

Researcher notes

Evidence is sparse. The bundle names utils.set and links to upstream code, but does not provide a fixed version or vendor advisory details beyond Snyk. The affected version data lists “0” while the description says all versions; verify package metadata before closure.

Mitigation direction

  • Inventory applications and services for the merge-change package.
  • Check Snyk and upstream vendor guidance for patched or replacement options.
  • Remove or replace merge-change where practical if no fixed version is available.
  • Prevent untrusted input from reaching affected merge-change utility paths.
  • Prioritize internet-facing applications that process user-supplied structured data.

Validation and detection

  • Review package manifests and lockfiles for merge-change.
  • Confirm whether merge-change is bundled transitively in production builds.
  • Trace application calls that pass external data into merge-change utilities.
  • Add regression tests covering unsafe object-path handling at application boundaries.
  • Document trusted-only usage if no attacker-controlled path exists.
Prepared
Confidence
medium
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

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CVE-2021-23421 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.6 (3.1)
Known Exploited
No
Published

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

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
5.6CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:U/RC:R2.23.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.6Medium
CVSS 3.1 vector shape for CVE-2021-23421Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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/amerge-change0Listed
Weakness

CWE details

No CWE listed

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