CVE-2022-20549 in Android
Summary
by MITRE • 12/16/2022
In authToken2AidlVec of KeyMintUtils.cpp, there is a possible out of bounds write due to an incorrect bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-13Android ID: A-242702451
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2022-20549 resides within the Android keymaster implementation, specifically in the authToken2AidlVec function located in KeyMintUtils.cpp. This flaw represents a critical security weakness that could enable local privilege escalation, allowing an attacker with system-level execution privileges to potentially gain elevated access within the Android security framework. The vulnerability manifests as an out-of-bounds write condition that occurs due to an incorrect bounds check implementation within the cryptographic authentication token processing mechanism.
The technical root cause of this vulnerability stems from improper validation of array boundaries during the conversion of authentication tokens to aidl vector structures. When processing cryptographic authentication data, the function fails to properly verify the size constraints of input data before performing memory operations, creating a scenario where maliciously crafted input could overwrite adjacent memory locations. This type of vulnerability falls under the CWE-129 weakness category, specifically addressing insufficient bounds checking in array access operations. The improper bounds verification allows an attacker to manipulate memory layout and potentially overwrite critical data structures or function pointers within the keymaster service execution context.
From an operational perspective, exploitation of this vulnerability requires an attacker to already possess system execution privileges, which significantly limits the attack surface but does not eliminate the risk entirely. The local escalation of privilege threat means that any malicious application or service running with system-level permissions could potentially leverage this flaw to gain further control over the device's cryptographic security infrastructure. This vulnerability impacts Android 13 systems and represents a serious concern for device security, particularly in environments where system-level applications may be compromised or where device management policies are not properly enforced. The Android ID A-242702451 indicates this issue was properly tracked within Google's internal vulnerability management system, highlighting the recognized severity of the flaw.
Mitigation strategies for this vulnerability should focus on immediate patch deployment through official Android security updates, which typically involve correcting the bounds checking logic in the KeyMintUtils.cpp file to properly validate input data size before memory operations. Organizations should implement robust monitoring for suspicious system-level processes and maintain strict access controls to prevent unauthorized privilege escalation. The vulnerability aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" and T1547.001 which addresses "Registry Run Keys / Startup Folder" - though in this case the escalation occurs through cryptographic service manipulation rather than traditional registry modifications. Security teams should also consider implementing memory protection mechanisms such as stack canaries and address space layout randomization to further reduce exploitability, while maintaining comprehensive logging of keymaster service operations to detect potential exploitation attempts.