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How CVE-2026-0056 Works (Out‑of‑Bounds Read in `ResourceTypes.cpp`)
The flaw resides in the `setTo` method of ResourceTypes.cpp, a core component responsible for parsing and managing Android’s compiled resource files (e.g., resources.arsc). When an app requests a resource, the framework loads a chunk of memory that contains the resource data. The `setTo` method is used to point a resource‑pool object to a specific memory region.
In vulnerable versions, the function performs an incorrect bounds check when copying or referencing the incoming resource data. More precisely, the code does not verify that the length of the supplied resource chunk (usually a string pool) does not exceed the allocated buffer’s size. An attacker can craft a malicious resource file where the declared length is artificially inflated beyond the actual buffer limits. Because the validation logic is flawed, the `setTo` method does not reject such oversized chunks.
When the framework later reads data from this resource pool – for instance, to extract a string or a key – it uses the inflated length value as an index. This leads to a read‑out‑of‑bounds condition, allowing the attacker to access memory locations that lie outside the intended resource buffer. The leaked memory can contain sensitive information from other processes or the kernel, such as authentication tokens, cryptographic keys, or parts of the system’s address space.
The attack requires no user interaction and can be triggered by any application that can supply a malicious resource file (e.g., by installing a specially crafted APK or by delivering a tainted resource over a local channel). Since no additional execution privileges are needed, a low‑privileged app can silently exfiltrate sensitive data from the device.
DailyCVE Form:
Platform: Android (AOSP)
Version: 14, 15, 16, 16‑qpr2
Vulnerability: Out‑of‑bounds read
Severity: High
Date: 2026‑06‑01
Prediction: 2026‑06‑03 (patch expected)
What Undercode Say:
Check if device is vulnerable (requires root or debug build) adb shell getprop ro.build.version.security_patch If patch level < 2026-06-01, device is at risk Dump currently loaded resource pools (example for forensic analysis) adb shell dumpsys package resources | grep -A5 "Resource Chunk" Monitor for out‑of‑bounds reads using Kernel Address Sanitizer (KASAN) on a debug build adb shell "echo 1 > /sys/kernel/debug/kasan/trace"
Code snippet – vulnerable logic (simplified):
// libs/utils/ResourceTypes.cpp (vulnerable version)
status_t ResStringPool::setTo(const void data, size_t size, bool copyData) {
const ResStringPool_header header = (const ResStringPool_header)data;
// Incorrect bounds check – does not validate header->stringCount against size
if (header->stringCount > 0) {
// Out‑of‑bounds read occurs here
mStrings = (const char16_t)(((const uint8_t)data) + header->stringsStart);
}
}
Patch added (expected fix):
// Validate that stringsStart + required bytes does not exceed total size
if (header->stringsStart + (header->stringCount sizeof(char16_t)) > size) {
return BAD_TYPE;
}
Exploit:
- Craft a malicious APK containing a resource file with a fake `stringCount` larger than the actual buffer.
- Install the APK on a vulnerable Android device (Android 14–16‑qpr2).
- Trigger resource parsing by launching an activity that accesses the tainted resource (e.g., via
getResources().getString(...)). - The `setTo` method accepts the oversized chunk; subsequent reads leak adjacent memory.
- Extract leaked data – potentially sensitive information like `Intent` data, credentials, or memory addresses.
Proof‑of‑concept triggers:
Use aapt2 to inject a malformed string pool aapt2 compile --legacy -o malicious.apk resource.arsc Install and run the crafted app adb install malicious.apk adb shell am start -n com.attacker/.MainActivity
Protection:
- Apply the June 2026 security update (patch level `2026-06-01` or later).
- Enable Google Play Protect – it blocks known malicious APKs that attempt to exploit this flaw.
- Avoid installing apps from untrusted sources – the attack vector requires the malformed resource to be present on the device.
- For OEMs/enterprises: Cherry‑pick the AOSP fix for `ResourceTypes.cpp` (commit ID will be published in the bulletin).
- Monitor for suspicious resource parsing errors in `logcat` (look for `ResStringPool::setTo` failures).
Impact:
- Confidentiality: High – an unprivileged app can read arbitrary memory, potentially leaking secrets or memory layout.
- Integrity: None – the flaw does not allow writing to memory.
- Availability: None – no crash or DoS condition is required for exploitation.
- Scope: Local only – the attacker must have the ability to execute code on the device (e.g., via a sideloaded app).
- User interaction: None – the attack is fully automatic once the malicious resource is parsed.
Overall risk: High due to ease of exploitation (no privileges, no user interaction) and the potential to expose sensitive system data.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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