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Fencer Intel
medium 5.6

CVE-2021-23421 json

Prototype Pollution

published 5y ago modified 4mo ago also GHSA-f9cv-665r-275h , EUVD-2021-2051

cvss
5.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 65%
public exploits
0
none known

Summary

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

Is CVE-2021-23421 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

1.08% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • snyk.io https://snyk.io/vuln/SNYK-JS-MERGECHANGE-1310985 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.6 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
CNA 3.1 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
npm merge-change
<=1.8.1
 no fix listed

Affected products

  • n/a merge-change

Classification

Weakness
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes
  • CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes

References

Sources

Fencer Intel 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.