CVE-2021-23436
CVSS v3
9.8
CRITICAL
EPSS Score
1.8 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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.
Technical details
- Published
- 2021-09-01
Frequently asked questions
What is CVE-2021-23436?
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.
Is CVE-2021-23436 actively exploited?
Active exploitation of CVE-2021-23436 has not been confirmed. Its EPSS score was 1.8% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-23436?
CVE-2021-23436 has a CVSS v3 base score of 9.8 (CRITICAL severity).
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