CVE-2021-39782: 
NixOS vulnerability analysis and mitigation

In Telephony, there is a possible unauthorized modification of the PLMN SIM file due to a missing permission check in Android 12L. This vulnerability, identified as CVE-2021-39782, could lead to local escalation of privilege without requiring additional execution privileges or user interaction. The issue was discovered and tracked as Android ID: A-202760015 (MITRE CVE, NVD).

The vulnerability is characterized by a missing permission check in the Android Telephony component, specifically affecting the PLMN SIM file handling. It has been assigned a CVSS v3.1 Base Score of 7.8 (HIGH) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. The vulnerability is classified under CWE-269 (Improper Privilege Management) (NVD).

The vulnerability allows an attacker to perform unauthorized modifications to the PLMN SIM file. A successful exploitation could result in high impacts on confidentiality, integrity, and availability of the system, as indicated by the CVSS scoring. The attack requires local access but no user interaction, making it particularly concerning for device security (NVD).

The vulnerability has been addressed in Android 12L security updates. Users should ensure their devices are updated to the latest available security patch level that includes fixes for this vulnerability (Android Security Bulletin).