CVE-2023-20191 - Incorrect Authorization

Severity

75%

Complexity

39%

Confidentiality

60%

A vulnerability in the access control list (ACL) processing on MPLS interfaces in the ingress direction of Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass a configured ACL. This vulnerability is due to incomplete support for this feature. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to bypass an ACL on the affected device. There are workarounds that address this vulnerability. This advisory is part of the September 2023 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2023 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication .

CVSS 3.1 Base Score 7.5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N).

Demo Examples

Incorrect Authorization

CWE-863

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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