CVE-2021-23960

Mozilla: Use-after-poison for incorrectly redeclared JavaScript variables during GC

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Severity

Moderate

Red Hat Product Security

8.8

CVSS 3.1

Review impact separately from score.

Published · January 26, 2021

Updated · November 22, 2025

Description

The Mozilla Foundation Security Advisory describes this flaw as:

Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and a potentially exploitable crash.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.1 · 8.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE-626 · Null Byte Interaction Error (Poison Null Byte)