CVE-2026-58823: stpropnci Memory Corruption Privilege Escalation

CVE-2026-58823 Overview

CVE-2026-58823 is a memory safety vulnerability in the stpropnci_process_std function of stpropnci_std.cc, disclosed in the Android Security Bulletin for September 2026. The flaw stems from a missing bounds check that enables local escalation of privilege without additional execution privileges. Exploitation requires no user interaction. The vulnerability is classified under [CWE-120] (Buffer Copy without Checking Size of Input) and affects Android platform components processed through the stpropnci_std code path. A local attacker who can execute low-privileged code on the device can leverage the flaw to elevate privileges within the affected process context.

Critical Impact
A local attacker with low privileges can achieve privilege escalation with high impact to confidentiality, integrity, and availability, without any user interaction.

Affected Products

Android platform components implementing stpropnci_std.cc
Devices covered by the Android Security Bulletin dated 2026-09-01
See the Android Security Bulletin September 2026 for the authoritative device and patch-level list

Discovery Timeline

2026-09-08 - CVE-2026-58823 published to the National Vulnerability Database (NVD)
2026-09-08 - Last updated in NVD
Patch details are published in the Android Security Bulletin September 2026

Technical Details for CVE-2026-58823

Vulnerability Analysis

The vulnerability resides in stpropnci_process_std, a routine defined in stpropnci_std.cc. According to the advisory, the function fails to validate the size of input data before operating on a fixed-size memory region. This omission allows an attacker-controlled input to exceed the intended buffer boundary during processing. The resulting memory corruption can be leveraged to alter execution state within the affected process and escalate privileges locally. Because the affected process typically runs with elevated system-level privileges relative to the caller, successful exploitation grants the attacker access to resources otherwise restricted from unprivileged application contexts. No user interaction, social engineering, or additional execution rights are required.

Root Cause

The root cause is a missing bounds check in stpropnci_process_std prior to a memory operation on data derived from a caller-supplied source. Classified as [CWE-120], the defect allows a copy or write operation to proceed without verifying that the destination buffer can accommodate the input length. The advisory does not disclose the specific field or exact code path, and Google has not released additional technical detail beyond the bulletin entry.

Attack Vector

The attack vector is local. An attacker must already have the ability to execute code on the target device, typically through a low-privileged application installed on the affected Android device. The malicious application submits crafted input that reaches stpropnci_process_std, triggering the out-of-bounds memory operation. Successful exploitation yields elevated privileges within the affected service or process context. The complexity of the attack is low, and no privileges beyond those granted to a standard installed application are required.

No public proof-of-concept or exploit code is available at the time of publication. Refer to the Android Security Bulletin September 2026 for the vendor-provided description.

Detection Methods for CVE-2026-58823

Indicators of Compromise

No public indicators of compromise have been published for CVE-2026-58823.
Unexpected crashes, tombstones, or SIGSEGV events referencing stpropnci_std in logcat or crash reports may indicate exploitation attempts.
Applications requesting or gaining access to resources beyond their declared permissions on unpatched devices warrant investigation.

Detection Strategies

Enumerate installed Android devices and compare their reported security patch level against the 2026-09-01 patch level required by the bulletin.
Monitor mobile device management (MDM) telemetry for devices lagging behind the vendor-published patch level.
Review application install events on managed devices for unsigned or side-loaded packages that could deliver a local exploit.

Monitoring Recommendations

Collect Android crash and tombstone telemetry into a centralized log platform for correlation with process names touching stpropnci_std.
Track compliance metrics for device patch level and flag devices that have not received the September 2026 Android security update.
Alert on privilege escalation indicators such as unexpected process capability changes or unauthorized access to protected system properties.

How to Mitigate CVE-2026-58823

Immediate Actions Required

Apply the September 2026 Android security patch (patch level 2026-09-01 or later) on all managed devices as soon as it is available from the device manufacturer.
Inventory all Android endpoints and identify devices that cannot be updated to the required patch level.
Restrict installation of untrusted applications through MDM policy to reduce the local attack surface until patching is complete.
Educate users to install applications only from vetted sources such as the official device application store.

Patch Information

The fix is included in the Android security patch level 2026-09-01. Device manufacturers integrate the upstream fix into their firmware releases on independent schedules. Consult the Android Security Bulletin September 2026 for the source patch reference and consult the device vendor for the corresponding OEM firmware update.

Workarounds

No vendor-supplied workaround has been published. Patching remains the authoritative remediation.
Where patching is delayed, block installation of untrusted third-party applications through MDM configuration.
Enforce Google Play Protect and application allow-listing on managed devices to reduce the likelihood of a malicious local application being installed.

bash

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