CVE-2026-55290 Overview
CVE-2026-55290 is an out-of-bounds heap read vulnerability in the setTo function of ResourceTypes.cpp within the Android platform. The flaw stems from a missing bounds check, allowing a local attacker to read heap memory outside the intended buffer boundary. Successful exploitation results in local information disclosure without requiring user interaction or additional execution privileges. The vulnerability is cataloged under [CWE-120] (Buffer Copy without Checking Size of Input) and was published in the Android Security Bulletin.
Critical Impact
Local attackers with low privileges can read adjacent heap memory contents, potentially exposing sensitive process data without user interaction.
Affected Products
- Android platform components processing resource files
- ResourceTypes.cpp in the Android Asset Packaging framework
- Devices pending the September 2026 Android security patch level
Discovery Timeline
- 2026-09-08 - CVE-2026-55290 published to NVD
- 2026-09-10 - Last updated in NVD database
Technical Details for CVE-2026-55290
Vulnerability Analysis
The vulnerability resides in the setTo method implemented in ResourceTypes.cpp, a core component of the Android resource-parsing subsystem. The function processes string resource data but fails to validate input length against the allocated heap buffer size. This missing bounds check permits read operations to extend beyond the buffer boundary into adjacent heap memory.
An attacker with local access and low privileges can trigger the code path by supplying crafted resource data. The out-of-bounds read discloses heap contents that may contain sensitive process state, pointers, or fragments of other application data. The confidentiality impact is limited but requires no user interaction.
Root Cause
The root cause is the absence of length validation in setTo before performing memory read operations on caller-supplied resource strings. Under [CWE-120], the function trusts input size fields without confirming they fit within the destination buffer. When parsing malformed or truncated resource tables, the read index advances past the allocated region, exposing residual heap memory.
Attack Vector
Exploitation requires local code execution context, such as an installed application on the device. The attacker crafts a malformed resource file or provides tainted input to a service that invokes ResourceTypes::setTo. Processing triggers the out-of-bounds read, and the disclosed bytes can be exfiltrated through the calling application's normal channels. No privilege escalation or user interaction is required.
Detailed technical information is available in the Android Security Bulletin September 2026.
Detection Methods for CVE-2026-55290
Indicators of Compromise
- Applications repeatedly parsing malformed APK or ARSC resource files targeting the setTo code path
- Unexpected crashes or SIGSEGV signals originating from libandroidfw or resource-loading libraries
- Installation of applications from unverified sources requesting no permissions yet performing resource parsing
Detection Strategies
- Monitor Android device logs for anomalous resource-parsing errors and abnormal heap read faults referencing ResourceTypes.cpp
- Inspect installed applications for embedded malformed resource tables using static analysis of APK files
- Correlate application telemetry with the September 2026 Android patch level to identify unpatched fleet devices
Monitoring Recommendations
- Enroll mobile devices into a Mobile Threat Defense solution capable of flagging suspicious resource parsing behavior
- Track patch-level compliance across managed Android endpoints and alert on devices below the September 2026 security patch
- Review application install events for sideloaded packages that may exercise this local attack surface
How to Mitigate CVE-2026-55290
Immediate Actions Required
- Apply the September 2026 Android security patch level or later on all managed devices
- Restrict installation of applications from unknown sources through mobile device management policies
- Audit third-party applications processing untrusted resource files and remove those without verified provenance
Patch Information
Google addressed CVE-2026-55290 in the September 2026 Android security patch. Device manufacturers and carriers distribute the fix via monthly over-the-air updates. Administrators should confirm affected devices report a security patch level of 2026-09-01 or later. Refer to the Android Security Bulletin September 2026 for advisory details and source code links.
Workarounds
- Limit sideloading and enforce installation only from Google Play or approved enterprise app stores
- Disable or uninstall applications that parse untrusted resource files until the device receives the patch
- Enforce Google Play Protect scanning to identify potentially harmful applications leveraging this class of flaw
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.