CVE-2026-56889: Integer Overflow Privilege Escalation

CVE-2026-56889 Overview

CVE-2026-56889 is a permission bypass vulnerability in Android caused by an integer overflow condition [CWE-190]. The flaw exists in multiple locations within the affected components and allows local escalation of privilege to System-level execution. Exploitation requires no user interaction, and an attacker must already hold high privileges on the device to trigger the overflow. The issue was addressed in the Android Security Bulletin published for September 2026.

Critical Impact
Successful exploitation grants an attacker System execution privileges on the affected Android device, bypassing intended permission checks and expanding the local attack surface.

Affected Products

Android platform components referenced in the September 2026 Pixel Security Bulletin
Pixel devices receiving the 2026-09-01 security patch level
Downstream Android distributions incorporating the affected code paths

Discovery Timeline

2026-09-15 - CVE-2026-56889 published to the National Vulnerability Database
2026-09-17 - Last updated in NVD database

Technical Details for CVE-2026-56889

Vulnerability Analysis

The vulnerability is an integer overflow that leads to a permission bypass in multiple Android components. When an arithmetic operation exceeds the storage capacity of its integer type, the resulting wrapped value can cause the runtime to misjudge size, offset, or permission-related computations. In this case, the wrap-around allows a caller to bypass permission enforcement logic that would otherwise gate access to privileged System functionality.

Because the attack vector is local and requires high privileges, the vulnerability is most relevant as a post-compromise primitive. An attacker who has already obtained a foothold on the device can chain this flaw to elevate to System, gaining broad control over the platform. Confidentiality, integrity, and availability impacts are all rated high.

Root Cause

The root cause is unchecked arithmetic on values that feed into permission or bounds decisions. Google's advisory notes that the defect appears in multiple locations, indicating a shared pattern rather than an isolated coding error. See the Android Security Bulletin September 2026 for component-level detail.

Attack Vector

Exploitation is local and requires a process already running with high privileges. The attacker triggers the vulnerable code path with crafted inputs that force an integer wrap, causing the permission check to evaluate against attacker-controlled state. No user interaction is required. Once executed, the attacker inherits System execution privileges on the affected device.

No public proof-of-concept code is available for CVE-2026-56889. Refer to the vendor advisory for the affected component list.

Detection Methods for CVE-2026-56889

Indicators of Compromise

Unexpected processes running with System UID that were not spawned by legitimate platform services
Anomalous invocation patterns targeting the components listed in the September 2026 Android bulletin
Devices reporting a security patch level earlier than 2026-09-01 after the patch window

Detection Strategies

Inventory Android endpoints and flag any device whose reported patch level predates 2026-09-01
Correlate mobile telemetry with privilege transitions to identify unauthorized elevation to System
Review logs from mobile threat defense agents for exploitation attempts against the affected subsystems

Monitoring Recommendations

Enforce compliance policies that block or restrict access from Android devices missing the September 2026 patch
Monitor enterprise mobility management (EMM) dashboards for delayed patch adoption across the fleet
Track application behavior for privileged API calls that deviate from documented app baselines

How to Mitigate CVE-2026-56889

Immediate Actions Required

Apply the Android security patch level 2026-09-01 or later on all managed Pixel and Android devices
Prioritize patch deployment on devices used by administrators or privileged accounts
Restrict installation of untrusted applications that could serve as the initial foothold required for exploitation

Patch Information

Google addressed CVE-2026-56889 in the September 2026 Android Security Bulletin. Devices running the 2026-09-01 security patch level or later contain the fix. Consult the Android Security Bulletin September 2026 for build numbers and per-component references.

Workarounds

No vendor-supplied workaround is available; patching is the required remediation
Reduce local attack surface by limiting sideloaded applications and enforcing Play Protect on managed devices
Apply conditional access policies that gate corporate resources on device patch compliance

bash

# Verify Android security patch level on a connected device
adb shell getprop ro.build.version.security_patch
# Expected output for remediated devices: 2026-09-01 or later