{
    "id": "CVE-2020-6820",
    "published": "2020-04-24 16:15:13",
    "last_modified": "2026-06-17 03:23:51",
    "cvss_score": "8.1",
    "cvss_severity": "HIGH",
    "cvss_version": "3.1",
    "cvss_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
    "cwe": "CWE-362",
    "description": "Under certain conditions, when handling a ReadableStream, a race condition can cause a use-after-free. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Thunderbird < 68.7.0, Firefox < 74.0.1, and Firefox ESR < 68.6.1.",
    "epss_score": "0.07063",
    "epss_percentile": "0.93989",
    "kev": 1,
    "kev_due": "2022-05-03",
    "has_exploit": 0,
    "updated_at": "2026-09-27 18:17:27",
    "priority": {
        "rank": 1,
        "label": "Patch first",
        "why": "On CISA KEV — known exploited in the wild, due 2022-05-03."
    },
    "products": [
        {
            "vendor": "mozilla",
            "product": "firefox"
        },
        {
            "vendor": "mozilla",
            "product": "thunderbird"
        }
    ],
    "kev_detail": {
        "cve_id": "CVE-2020-6820",
        "date_added": "2021-11-03",
        "due_date": "2022-05-03",
        "vendor": "Mozilla",
        "product": "Firefox and Thunderbird",
        "name": "Mozilla Firefox And Thunderbird Use-After-Free Vulnerability",
        "ransomware": 0
    },
    "exploits": [],
    "refs_list": [
        "https://bugzilla.mozilla.org/show_bug.cgi?id=1626728",
        "https://usn.ubuntu.com/4335-1/",
        "https://www.mozilla.org/security/advisories/mfsa2020-11/",
        "https://www.mozilla.org/security/advisories/mfsa2020-14/",
        "https://bugzilla.mozilla.org/show_bug.cgi?id=1626728",
        "https://usn.ubuntu.com/4335-1/",
        "https://www.mozilla.org/security/advisories/mfsa2020-11/",
        "https://www.mozilla.org/security/advisories/mfsa2020-14/",
        "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-6820"
    ]
}