The Android security team is responsible for managing security vulnerabilities discovered in the Android platform and many of the core Android apps bundled with Android devices.
The Android security team finds security vulnerabilities through internal research and also responds to bugs reported by third parties. Sources of external bugs include issues reported through the vulnerability form, published and prepublished academic research, upstream open source project maintainers, notifications from our device manufacturer partners, and publicly disclosed issues posted on blogs or social media.
Reporting security issues
Any developer, Android user, or security researcher can notify the Android security team of potential security issues through the vulnerability form.
Bugs marked as security issues aren't externally visible, but they may eventually be made visible after the issue is evaluated or resolved. If you plan to submit a patch or Compatibility Test Suite (CTS) test to resolve a security issue, please attach it to the bug report and wait for a response before uploading the code to AOSP.
The first task in handling a security vulnerability is to identify the severity of the bug and which component of Android is affected. The severity determines how the issue is prioritized, and the component determines who fixes the bug, who is notified, and how the fix gets deployed to users.
This table covers the definitions of hardware and software security contexts. The context can be defined by the sensitivity of data it typically processes or the area in which it runs. Not all security contexts are applicable to all systems. This table is ordered from least to most privileged.
|Context type||Type definition|
A restricted execution environment where only the most minimal of
permissions are provided.
For example, trusted applications processing untrusted data within a sandboxed environment.
|Unprivileged context||A typical execution environment expected by unprivileged code.
For example, an Android application that runs in an SELinux domain with the
|Privileged context||A privileged execution environment which may have access to elevated
permissions, handles multiple user PII, and/or maintains system
For example, an Android application with capabilities that would be forbidden by the SELinux
|OS Kernel||Functionality that:
|Trusted Hardware Base (THB)||Discrete hardware components, generally on the SoC, which provide functionality critical to the core use cases of the device (such as, cellular basebands, DSPs, GPUs, and ML processors).|
|Bootloader Chain||A component that configures the device on boot and then passes control to the Android OS.|
|Trusted Execution Environment (TEE)||A component that is designed to be protected from even a hostile OS Kernel (for example, TrustZone and hypervisors, such as pKVM, which protect Virtual Machines from the OS Kernel).|
|Secure Enclave / Secure Element (SE)||An optional hardware component designed to be protected from all other
components on the device and from physical attack, as defined in Introduction to Secure Elements.
This includes the Titan-M chip present in some Android devices.
The severity of a bug generally reflects the potential harm that could occur if a bug was successfully exploited. Use the following criteria to determine the severity.
|Rating||Consequence of successful exploitation|
|Negligible Security Impact (NSI)||
While the severity of security vulnerabilities is often easy to identify, ratings may change based on circumstances.
|Requires running as a privileged context to execute the attack (not applicable to TEE, SE, and hypervisors such as pKVM)||-1 Severity|
|Vulnerability-specific details limit the impact of the issue||-1 Severity|
|Biometric authentication bypass that requires biometric information directly from the device owner||-1 Severity|
|Compiler or platform configurations mitigate a vulnerability in the source code||Moderate Severity if the underlying vulnerability is Moderate or higher|
|Requires physical access to device internals and is still possible if the device is off or hasn't been unlocked since being powered on||-1 Severity|
|Requires physical access to device internals while the device is on and has previously been unlocked||-2 Severity|
|A local attack that requires the bootloader chain to be unlocked||No higher than Low|
|A local attack that requires Developer Mode or any persistent developer mode settings to be currently enabled on the device (and isn't a bug in Developer Mode itself).||No higher than Low|
|If no SELinux domain can conduct the operation under the Google-provided SEPolicy||Negligible Security Impact|
Local versus Proximal versus Remote
A remote attack vector indicates that the bug can be exploited without installing an app or without physical access to a device. This includes bugs that can be triggered by browsing to a web page, reading an email, receiving an SMS message, or connecting to a hostile network. For the purpose of our severity ratings, we also consider "proximal" attack vectors as remote. These include bugs that can be exploited only by an attacker who is physically near the target device, for example, a bug that requires sending malformed Wi-Fi or Bluetooth packets. We consider Ultra-wideband (UWB) and NFC-based attacks as proximal and therefore remote.
Local attacks require the victim to run an app, either by installing and running an app or by consenting to run an Instant App. Paired companion devices will be considered as local. For the purpose of severity ratings, the Android security team also consider physical attack vectors as local. These include bugs that can be exploited only by an attacker who has physical access to the device, for example a bug in a lock screen or one that requires plugging in a USB cable.
Android assumes that all networks are hostile and could be injecting attacks or spying on traffic. While link-layer security (for example, Wi-Fi encryption) secures communication between a device and the Access Point it's connected to, it does nothing to secure the remaining links in the chain between the device and the servers it's communicating with.
By contrast, HTTPS typically protects the entire communication end to end, encrypting the data at its source, then decrypting and verifying it only once it's reached its final destination. Because of this, vulnerabilities that compromise link-layer network security are rated less severe than vulnerabilities in HTTPS/TLS: Wi-Fi encryption alone is insufficient for most communication on the internet.
Biometric authentication is a challenging space, and even the best systems can be fooled by a near-match (see Android Developers Blog: Lockscreen and authentication improvements in Android 11). These severity ratings distinguish between two classes of attacks and are intended to reflect the actual risk to the end user.
The first class of attacks allows bypassing biometric authentication in a generalizable way, without high quality biometric data from the owner. If, for instance, an attacker can place a piece of gum on a fingerprint sensor, and it grants access to the device based on residue left on the sensor, that's a simple attack that could be performed on any susceptible device. It doesn't require any knowledge of the device's owner. Given that it's generalizable and potentially impacts a larger number of users, this attack receives the full severity rating (for example, High, for a Lockscreen bypass).
The other class of attacks generally involves a presentation attack instrument (spoof) based on the device owner. Sometimes this biometric information is relatively easy to get (for example, if someone's profile picture on social media is sufficient to fool biometric auth, then a biometric bypass would receive the full severity rating). But if an attacker would need to acquire biometric data directly from the device owner (for example, an infrared scan of their face), that's a significant enough barrier that it limits the number of people affected by the attack, so there's a -1 modifier.
SYSTEM_ALERT_WINDOW and Tapjacking
For information about our policies regarding
and tapjacking, see the "Tapjacking/overlay SYSTEM_ALERT_WINDOW
vulnerability on a non-security-critical screen" section of BugHunter
Bugs with no security impact page.
Multi-user security in Android Automotive OS
Android Automotive OS adopts a multi user security model different from the other form factors. Each Android user is intended to be used by a different physical person. For example, a temporary guest user can be assigned to a friend who borrows the vehicle from the car's owner. To accommodate use cases like this, users by default have access to necessary components needed to use the vehicle, such as Wi-Fi and cellular network settings.
The development team responsible for fixing the bug depends on which component the bug is in. It could be a core component of the Android platform, a kernel driver supplied by an original equipment manufacturer (OEM), or one of the preloaded apps on Pixel devices.
Bugs in AOSP code are fixed by the Android engineering team. Low-severity bugs, bugs in certain components, or bugs that are already publicly known may be fixed directly in the publicly available AOSP main branch; otherwise they're fixed in our internal repositories first.
The component is also a factor in how users get updates. A bug in the framework or kernel requires an over-the-air (OTA) firmware update that each OEM needs to push. A bug in an app or library published in Google Play (for example, Gmail, Google Play Services, or WebView) can be sent to Android users as an update from Google Play.
When a security vulnerability in AOSP is fixed in an Android Security Bulletin, we'll notify Android partners of issue details and provide patches. The list of backport-supported versions changes with each new Android release. Contact your device manufacturer for the list of supported devices.
Releasing code to AOSP
If the security bug is in an AOSP component, the fix is pushed out to AOSP after the OTA is released to users. Fixes for low-severity issues may be submitted directly to the AOSP main branch before a fix is available to devices through an OTA.
Receiving Android updates
Updates to the Android system are generally delivered to devices through OTA update packages. These updates may come from the OEM who produced the device or the carrier who provides service to the device. Google Pixel device updates come from the Google Pixel team after going through a carrier technical acceptance (TA) testing procedure. Google also publishes Pixel factory images that can be side-loaded to devices.
Updating Google services
In addition to providing patches for security bugs, the Android security team reviews security bugs to determine if there are other ways to protect users. For example, Google Play scans all apps and removes any app that attempts to exploit a security bug. For apps installed from outside of Google Play, devices with Google Play Services may also use the Verify Apps feature to warn users about apps that may be potentially harmful.
Information for Android app developers: https://developer.android.com
Security information exists throughout the Android Open Source and Developer sites. Good places to start:
Sometimes the Android Security team publishes reports or whitepapers. See Security Reports for more details.