68%
9%
98%
IOMMU page mapping issues on x86 T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Both AMD and Intel allow ACPI tables to specify regions of memory which should be left untranslated, which typically means these addresses should pass the translation phase unaltered. While these are typically device specific ACPI properties, they can also be specified to apply to a range of devices, or even all devices. On all systems with such regions Xen failed to prevent guests from undoing/replacing such mappings (CVE-2021-28694). On AMD systems, where a discontinuous range is specified by firmware, the supposedly-excluded middle range will also be identity-mapped (CVE-2021-28695). Further, on AMD systems, upon de-assigment of a physical device from a guest, the identity mappings would be left in place, allowing a guest continued access to ranges of memory which it shouldn't have access to anymore (CVE-2021-28696).
CVSS 3.1 Base Score 6.8. CVSS Attack Vector: physical. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
CVSS 2.0 Base Score 4.6. CVSS Attack Vector: local. CVSS Attack Complexity: low. CVSS Vector: (AV:L/AC:L/Au:N/C:P/I:P/A:P).
The following code could be for a medical records application. It displays a record to already authenticated users, confirming the user's authorization using a value stored in a cookie.
}}setcookie("role", $role, time()+60*60*2);die("\n");DisplayMedicalHistory($_POST['patient_ID']);die("You are not Authorized to view this record\n");The programmer expects that the cookie will only be set when getRole() succeeds. The programmer even diligently specifies a 2-hour expiration for the cookie. However, the attacker can easily set the "role" cookie to the value "Reader". As a result, the $role variable is "Reader", and getRole() is never invoked. The attacker has bypassed the authorization system.
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