The exploitation chain utilizes a surviving signal entry as an oracle to confirm memory reclamation before executing a series of heap-based maneuvers to overwrite kernel credentials. The released exploit proof-of-concept (PoC) automates this process using timing windows and ptrace-based memory manipulation to achieve a root shell. Given the publication of functional exploit code, Android devices utilizing the affected InfinityCore Signal subsystem are at elevated risk of local privilege escalation.

Attack Chain

1. The attacker forks a controller process to orchestrate the race condition across multiple timing windows.
2. The controller forks child processes that invoke exit_group to trigger thread death and initiate signal cleanup.
3. A non-leader thread floods the system with 20,000 per-thread timers against the old leader to force sigqueue event generation.
4. An execveat system call is triggered to induce the race condition during the cleanup of the signal queue.
5. The post-exec process scans the residual pending queue and reclaims freed objects using a ktimer heap spray.
6. The exploit decodes the freelist to identify object addresses and uses a ptrace parent process to perform AIO (Asynchronous I/O) page reclaim.
7. A forged timer is triggered to finalize kernel memory corruption.
8. The exploit overwrites the process credentials in the kernel, resulting in a shell with root privileges.

Impact

Successful exploitation of CVE-2026-98256 results in local privilege escalation, granting an attacker root access to the underlying Android system. This bypasses standard Android security boundaries, allowing for full system compromise, data exfiltration, and the persistence of malicious code at the kernel level. The exploit targets ARM64-based Android kernels and requires local access to the device.

Recommendation

Prioritized actions for security teams:

• Identify all Android devices in the fleet running kernels incorporating the InfinityCore Signal subsystem and verify patching status against vendor security bulletins.
• Prioritize patching for all devices running affected ARM64-based Android kernel builds.
• Implement kernel-level monitoring for suspicious ptrace calls and unusual signal queue activity if telemetry is available.
• Since this is a local privilege escalation (LPE), ensure robust device management policies are in place to restrict unauthorized application installation and sideloading, which could facilitate the deployment of this exploit.

Attack Chain

1. The exploit performs initial environment probing by calling prctl(PR_FUTEX_HASH, GET_SLOTS) to confirm kernel compatibility.
2. The process enters an iterative loop (up to 256 times) to manipulate the Futex hash layout, setting hash slots to 8.
3. A helper process is spawned and synchronized using clock_nanosleep(TIMER_ABSTIME) to facilitate precise preemption timing.
4. A target process is created, which acquires a warm lock before dropping its scheduling priority to SCHED_IDLE (nice 19) to create the race window.
5. The primary controller resizes the Futex hash to 2^18, triggering the race condition while the helper process is sleeping.
6. The exploit floods the system with pipe structures to reclaim the memory previously freed by the Futex hash release.
7. The attacker-controlled memory inside the pipe buffer is used to overwrite the task_struct->cred object in the kernel.
8. Upon successful overwrite, the process UID is elevated to zero, resulting in the execution of a root-privileged /system/bin/sh shell.

Impact

The vulnerability allows any local unprivileged application or user on an affected Android device to achieve full root privileges. Successful exploitation results in complete compromise of the device's security model, bypassing all permission boundaries and allowing for arbitrary code execution with kernel-level authority, data exfiltration, and persistent access.

Recommendation

1. Monitor for kernel updates from InfinityCore and apply the patch addressing CVE-2026-80775 immediately.
2. Implement kernel-level integrity monitoring to detect anomalous modifications to task_struct credentials.
3. Restrict the ability of untrusted applications to utilize advanced Futex operations or custom system call flags if the kernel interface can be hardened.
4. Perform memory forensic analysis on devices suspected of unauthorized privilege escalation to identify potential use-after-free corruption artifacts.

This results in memory corruption that an attacker can leverage to target the reference counter of a private futex hash. By reclaiming the freed hash memory using a pipe ring, an attacker can manipulate kernel structures to overwrite the task_struct->cred, effectively granting the attacker root privileges. Successful exploitation requires specific kernel configurations: CONFIG_SCHED_CACHE must be enabled, sched_cache_active must be active at runtime, the system must support SD_SHARE_LLC with multiple CPUs, and sysctl_sched_cache_user must not be set to zero.

Attack Chain

1. Attacker initializes a malicious environment by confirming CONFIG_SCHED_CACHE=y and sysctl_sched_cache_user != 0.
2. The exploit process uses sched_setattr to establish scheduling parameters for capability verification.
3. The process allocates a 128 MB address space buffer to facilitate page churn.
4. A victim process is forked and set to SCHED_IDLE, periodically invoking execve to free its own mm_struct.
5. A helper thread creates page fluctuations using readv(/dev/zero) and nanosleep to induce the race condition.
6. The main thread performs an iterative loop (up to 4096 times) of sched_setattr to trigger the use-after-free in the futex hash.
7. The exploit reclaims the freed futex hash memory using a pipe ring to facilitate arbitrary data manipulation.
8. The exploit overwrites the task_struct->cred of the current process to set the UID to zero, followed by spawning /system/bin/sh.

Impact

Successful exploitation of CVE-2026-98385 results in a complete compromise of the affected Android device. An unprivileged attacker can transition to root privileges, bypassing system security controls and gaining full read/write access to the device filesystem, user data, and system binaries. This vulnerability impacts any Android implementation utilizing the vulnerable InfinityCore scheduler code path with the specified kernel configurations enabled.

Recommendation

1. Audit kernel configurations on Android deployments to verify if CONFIG_SCHED_CACHE is enabled; if unnecessary, disable the feature in the kernel build.
2. Monitor and restrict the sysctl_sched_cache_user setting; ensure it is set to zero if the scheduler cache feature is not required for production workloads.
3. Implement kernel-level integrity monitoring to detect anomalous writes to the task_struct structure.
4. Deploy updates provided by the device manufacturer or InfinityCore maintainers that apply the patch for CVE-2026-98385.
5. Perform local security assessments using kernel BTF or vmlinux symbols to identify if the target kernel is susceptible to the defined structure offsets in the LPE chain.