CVE-2026-28664 Overview
CVE-2026-28664 is a local privilege escalation vulnerability in the WriteImageToDisk function of runtime_image.cc in Android. A logic error in the code allows an attacker with local access to tamper with files written to disk. Successful exploitation grants elevated privileges without requiring additional execution permissions or user interaction. The vulnerability is categorized under [CWE-693] (Protection Mechanism Failure) and was published in the Android Security Bulletin for September 2026.
Critical Impact
A local attacker with low privileges can tamper with disk images to escalate privileges on affected Android devices without user interaction.
Affected Products
- Android (component: runtime_image)
- Devices receiving the September 2026 Android Security Bulletin patch level
- Refer to the Android Security Bulletin September 2026 for the exact patch level and affected versions
Discovery Timeline
- 2026-09-08 - CVE-2026-28664 published to NVD
- 2026-09-08 - Last updated in NVD database
Technical Details for CVE-2026-28664
Vulnerability Analysis
The flaw resides in the WriteImageToDisk function within runtime_image.cc. This function is responsible for writing runtime image data to persistent storage. A logic error in the implementation permits an attacker to tamper with the file contents during the write operation. Because the affected process operates with elevated privileges, tampered image data can be used to influence subsequent execution paths and gain higher privileges on the device.
The vulnerability requires only local access and low privileges. No user interaction is needed to trigger the code path. The confidentiality, integrity, and availability impact are all high because a successful attacker can modify trusted runtime artifacts consumed by privileged components.
Root Cause
The root cause is a protection mechanism failure ([CWE-693]) in the file-write logic. The function fails to properly enforce integrity or access controls when persisting runtime image data. This gap allows an attacker who can invoke or race the write path to alter the resulting file, defeating the intended security boundary between low-privileged callers and privileged consumers of the image.
Attack Vector
An attacker must have local access and low privileges on the target Android device, such as those granted to an installed third-party application. The attacker interacts with the vulnerable code path in runtime_image.cc to trigger the flawed write logic. Once the tampered image is loaded by a privileged component, the attacker gains elevated privileges. No social engineering or additional execution privileges are required.
No public proof-of-concept exploit code is available at the time of publication. For technical background, refer to the Android Security Bulletin September 2026.
Detection Methods for CVE-2026-28664
Indicators of Compromise
- Unexpected modifications to runtime image files produced by the runtime_image component
- Privileged Android system processes loading runtime images with mismatched checksums or unexpected timestamps
- Third-party applications invoking system APIs that trigger WriteImageToDisk outside of normal usage patterns
Detection Strategies
- Monitor Android device patch levels and flag devices that have not applied the September 2026 security bulletin
- Inspect installed applications for behaviors that repeatedly invoke runtime image write operations
- Correlate mobile device telemetry with known-good baselines for system file integrity
Monitoring Recommendations
- Enroll Android devices in a mobile threat defense solution capable of flagging unpatched OS versions and anomalous privileged operations
- Track Android Security Bulletin advisories and validate patch adoption across the device fleet
- Log and review application installation events to identify suspicious apps targeting local privilege escalation flaws
How to Mitigate CVE-2026-28664
Immediate Actions Required
- Apply the September 2026 Android security patch level on all affected devices as soon as the vendor makes it available
- Restrict installation of untrusted third-party applications, which are the primary vehicle for local exploitation
- Enforce mobile device management (MDM) policies that require the latest security patch level for corporate access
Patch Information
Google addressed CVE-2026-28664 in the September 2026 Android Security Bulletin. Device manufacturers must integrate the upstream fix and distribute updates to end users. Consult the Android Security Bulletin September 2026 for the specific patch level (2026-09-01 or later) that remediates this issue.
Workarounds
- No official vendor workaround is documented; patching is the recommended remediation
- Limit device exposure by disallowing sideloaded applications and restricting app installations to vetted sources
- Segment corporate access so that devices missing the September 2026 patch level cannot reach sensitive resources
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.