HOMEVULNERABILITIESCVE-2021-23436
CRITICAL

CVE-2021-23436

CWE-843Published: September 1, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

This affects the package immer before 9.0.6. A type confusion vulnerability can lead to a bypass of CVE-2020-28477 when the user-provided keys used in the path parameter are arrays. In particular, this bypass is possible because the condition (p === "__proto__" || p === "constructor") in applyPatches_ returns false if p is ['__proto__'] (or ['constructor']). The === operator (strict equality operator) returns false if the operands have different type.

NVD Source

Technical Analysis

CVE-2021-23436 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

immer_project1 product(s)
immer
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/immerjs/immer/commit/fa671e55ee9bd42ae08cc239102b665a23958237
PATCHhttps://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1579266
PATCHhttps://snyk.io/vuln/SNYK-JS-IMMER-1540542
PATCHhttps://github.com/immerjs/immer/commit/fa671e55ee9bd42ae08cc239102b665a23958237
PATCHhttps://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1579266
PATCHhttps://snyk.io/vuln/SNYK-JS-IMMER-1540542

All References (6)

→
https://github.com/immerjs/immer/commit/fa671e55ee9bd42ae08cc239102b665a23958237Patch · Third Party Advisory
→
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1579266Exploit · Patch · Third Party Advisory
→
https://snyk.io/vuln/SNYK-JS-IMMER-1540542Exploit · Patch · Third Party Advisory
→
https://github.com/immerjs/immer/commit/fa671e55ee9bd42ae08cc239102b665a23958237Patch · Third Party Advisory
→
https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-1579266Exploit · Patch · Third Party Advisory
→
https://snyk.io/vuln/SNYK-JS-IMMER-1540542Exploit · Patch · Third Party Advisory

Quick Facts

CVE IDCVE-2021-23436
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-843
CISA KEVNo
Affected1 vendor(s)
PublishedSep 1, 2021

Related CVEs (CWE-843)

CVE-2021-33970
10.0
CVE-2010-2299
10.0
CVE-2022-48511
9.8
CVE-2023-26063
9.8
CVE-2023-25933
9.8
CVE-2023-23557
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-23436 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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