{
    "id": "CVE-2021-22991",
    "published": "2021-03-31 18:15:14",
    "last_modified": "2026-06-17 03:38:10",
    "cvss_score": "9.8",
    "cvss_severity": "CRITICAL",
    "cvss_version": "3.1",
    "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
    "cwe": "CWE-119",
    "description": "On BIG-IP versions 16.0.x before 16.0.1.1, 15.1.x before 15.1.2.1, 14.1.x before 14.1.4, 13.1.x before 13.1.3.6, and 12.1.x before 12.1.5.3, undisclosed requests to a virtual server may be incorrectly handled by the Traffic Management Microkernel (TMM) URI normalization, which may trigger a buffer overflow, resulting in a DoS attack. In certain situations, it may theoretically allow bypass of URL based access control or remote code execution (RCE). Note: Software versions which have reached End of Software Development (EoSD) are not evaluated.",
    "epss_score": "0.61064",
    "epss_percentile": "0.99132",
    "kev": 1,
    "kev_due": "2022-02-01",
    "has_exploit": 0,
    "updated_at": "2026-09-26 18:27:18",
    "priority": {
        "rank": 1,
        "label": "Patch first",
        "why": "On CISA KEV — known exploited in the wild, due 2022-02-01."
    },
    "products": [
        {
            "vendor": "f5",
            "product": "big-ip_access_policy_manager"
        },
        {
            "vendor": "f5",
            "product": "big-ip_advanced_firewall_manager"
        },
        {
            "vendor": "f5",
            "product": "big-ip_advanced_web_application_firewall"
        },
        {
            "vendor": "f5",
            "product": "big-ip_analytics"
        },
        {
            "vendor": "f5",
            "product": "big-ip_application_acceleration_manager"
        },
        {
            "vendor": "f5",
            "product": "big-ip_application_security_manager"
        },
        {
            "vendor": "f5",
            "product": "big-ip_ddos_hybrid_defender"
        },
        {
            "vendor": "f5",
            "product": "big-ip_domain_name_system"
        },
        {
            "vendor": "f5",
            "product": "big-ip_fraud_protection_service"
        },
        {
            "vendor": "f5",
            "product": "big-ip_global_traffic_manager"
        },
        {
            "vendor": "f5",
            "product": "big-ip_link_controller"
        },
        {
            "vendor": "f5",
            "product": "big-ip_local_traffic_manager"
        },
        {
            "vendor": "f5",
            "product": "big-ip_policy_enforcement_manager"
        },
        {
            "vendor": "f5",
            "product": "ssl_orchestrator"
        }
    ],
    "kev_detail": {
        "cve_id": "CVE-2021-22991",
        "date_added": "2022-01-18",
        "due_date": "2022-02-01",
        "vendor": "F5",
        "product": "BIG-IP Traffic Management Microkernel",
        "name": "F5 BIG-IP Traffic Management Microkernel Buffer Overflow",
        "ransomware": 0
    },
    "exploits": [],
    "refs_list": [
        "https://support.f5.com/csp/article/K56715231",
        "https://support.f5.com/csp/article/K56715231",
        "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22991"
    ]
}