VDB-223916 · CVE-2023-21020 · A-256591441

Google Android 13.0 main.c registerSignalHandlers use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.3	$0-$5k	0.00

Summaryinfo

A vulnerability classified as problematic was found in Google Android 13.0. Affected by this vulnerability is the function registerSignalHandlers of the file main.c. Such manipulation leads to use after free. This vulnerability is documented as CVE-2023-21020. The attack needs to be performed locally. There is not any exploit available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability was found in Google Android 13.0 (Smartphone Operating System) and classified as problematic. Affected by this issue is the function registerSignalHandlers of the file main.c. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In registerSignalHandlers of main.c, there is a possible local arbitrary code execution due to a use after free. 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-256591441

The weakness was released 03/25/2023 as A-256591441. The advisory is shared for download at source.android.com. This vulnerability is handled as CVE-2023-21020 since 11/03/2022. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/08/2025). It is expected to see the exploit prices for this product increasing in the near future.

Applying a patch is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2023-25188). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Smartphone Operating System

Vendor

Google

Name

Android

Version

13.0

License

free

Website

Vendor: https://www.google.com/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 4.2
VulDB Temp Score: 4.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 6.7
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔍

Timelineinfo

11/03/2022 🔍
03/25/2023 +142 days 🔍
03/25/2023 +0 days 🔍
09/08/2025 +898 days 🔍

Sourcesinfo

Vendor: google.com

Advisory: A-256591441
Status: Confirmed

CVE: CVE-2023-21020 (🔍)
GCVE (CVE): GCVE-0-2023-21020
GCVE (VulDB): GCVE-100-223916
EUVD: 🔍
scip Labs: https://www.scip.ch/en/?labs.20150917

Entryinfo

Created: 03/25/2023 08:20
Updated: 09/08/2025 05:09
Changes: 03/25/2023 08:20 (42), 02/24/2025 20:59 (26), 09/08/2025 05:09 (1)
Complete: 🔍
Cache ID: 216::103