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Fencer Vulns
medium 5.6

CVE-2021-23509 json

Prototype Pollution

published 2021-11-03 5 y ago modified 2026-06-17 4 mo ago also GHSA-8gwj-8hxc-285w , EUVD-2021-2324

cvss
5.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

This affects the package json-ptr before 3.0.0. A type confusion vulnerability can lead to a bypass of CVE-2020-7766 when the user-provided keys used in the pointer parameter are arrays.

Patch / fix

  • npm json-ptr 3.0.0
  • n/a json-ptr 3.0.0

Exploit prediction

1.83% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • snyk.io https://snyk.io/vuln/SNYK-JS-JSONPTR-1577291 referenced PoC, tagged "exploit" by a source, unverified
  • snyk.io https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1767165 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:P/RL:O/RC:C
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 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Affected packages

ecosystem package affected fixed in
npm json-ptr
<3.0.0
3.0.0

Affected products

  • n/a json-ptr

Classification

Weakness
  • CWE-843 Access of Resource Using Incompatible Type
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

References

Sources

Fencer Vulns 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.