Performing garbage collection on re-declared JavaScript variables resulted in a user-after-poison, and a potentially exploitable crash. This vulnerability affects Firefox < 85, Thunderbird < 78.7, and Firefox ESR < 78.7.

CNA Affected

[
  {
    "product": "Firefox",
    "vendor": "Mozilla",
    "versions": [
      {
        "status": "affected",
        "version": "< 85"
      }
    ]
  },
  {
    "product": "Thunderbird",
    "vendor": "Mozilla",
    "versions": [
      {
        "status": "affected",
        "version": "< 78.7"
      }
    ]
  },
  {
    "product": "Firefox ESR",
    "vendor": "Mozilla",
    "versions": [
      {
        "status": "affected",
        "version": "< 78.7"
      }
    ]
  }
]