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Vulnerability Database/CVE-2026-49884

CVE-2026-49884: NFC Stack Privilege Escalation Vulnerability

CVE-2026-49884 is a privilege escalation flaw in the NFC stack that enables local attackers to gain elevated privileges through an out of bounds write. This post explains its impact, affected versions, and mitigation steps.

Published:

CVE-2026-49884 Overview

CVE-2026-49884 is an out-of-bounds write vulnerability in the rw_mfc_handle_read_op function of rw_mfc.cc, a component of the Android Near Field Communication (NFC) stack. The flaw stems from an incorrect bounds check during Mifare Classic read operations. A local attacker with low privileges can trigger the condition to achieve local privilege escalation. Exploitation requires no user interaction and no additional execution privileges. The issue is tracked under CWE-120: Buffer Copy without Checking Size of Input and is addressed in the Android Security Bulletin September 2026.

Critical Impact

A local, low-privileged process can corrupt memory in an NFC handler to escalate privileges on the device without user interaction.

Affected Products

  • Android Open Source Project (AOSP) NFC stack containing rw_mfc.cc
  • Android devices covered by the September 2026 security patch level
  • Downstream vendor Android builds shipping the affected NFC component

Discovery Timeline

  • 2026-09-08 - CVE-2026-49884 published to the National Vulnerability Database (NVD)
  • 2026-09-01 - Fix included in the Android Security Bulletin September 2026
  • 2026-09-10 - Last updated in the NVD database

Technical Details for CVE-2026-49884

Vulnerability Analysis

The vulnerability resides in rw_mfc_handle_read_op, a handler in the Reader/Writer (RW) module that processes responses from Mifare Classic (MFC) tags. The function performs an incorrect bounds check before writing tag response data into a destination buffer. When the length of the incoming data is not properly validated against the destination buffer size, the function writes past the allocated region.

Because the NFC service runs with elevated privileges on Android, corrupting memory inside this handler enables an unprivileged local process to influence execution in a higher-privileged context. The result is local escalation of privilege without requiring the victim to interact with the device.

Root Cause

The root cause is an improper length validation in rw_mfc_handle_read_op within rw_mfc.cc. The bounds check does not correctly compare the attacker-influenced read length against the size of the destination buffer, allowing a linear out-of-bounds write [CWE-120].

Attack Vector

The attack vector is local. A malicious application or local process interacting with the NFC subsystem can craft or influence Mifare Classic read operation data that reaches the vulnerable handler. The handler then writes beyond the intended buffer boundary, corrupting adjacent memory used by the NFC service and enabling privilege escalation. No user interaction is required.

No public exploit code or proof-of-concept has been published for CVE-2026-49884. See the Android Security Bulletin September 2026 for authoritative technical details.

Detection Methods for CVE-2026-49884

Indicators of Compromise

  • Unexpected crashes or tombstones from the Android NFC service process referencing rw_mfc or rw_mfc_handle_read_op
  • Installation of untrusted applications that request or exercise NFC permissions immediately before service crashes
  • Devices running an Android security patch level earlier than 2026-09-01 that show anomalous NFC activity

Detection Strategies

  • Enforce a minimum Android security patch level of 2026-09-01 through mobile device management (MDM) compliance policies and flag non-compliant devices
  • Correlate NFC service crashes with recent application installs using endpoint telemetry from mobile security tooling
  • Review application manifests for the android.permission.NFC permission on unmanaged or sideloaded apps

Monitoring Recommendations

  • Ingest Android device logs and crash reports into a centralized data lake for pattern analysis across the fleet
  • Alert on repeated native crashes in com.android.nfc originating from the RW module
  • Track patch-level drift over time and prioritize remediation for devices exposed to untrusted app sources

How to Mitigate CVE-2026-49884

Immediate Actions Required

  • Apply the September 2026 Android security patch (patch level 2026-09-01 or later) to all managed devices
  • Restrict installation of applications from unknown sources through MDM policy
  • Audit installed applications holding NFC permissions and remove those that are unnecessary

Patch Information

Google addressed CVE-2026-49884 in the Android Security Bulletin September 2026. Device manufacturers integrate the AOSP fix into their vendor builds and distribute it through over-the-air updates. Administrators should verify that managed devices report a security patch level of 2026-09-01 or later.

Workarounds

  • Disable NFC on devices that do not require it until the security patch is applied
  • Limit device provisioning to models that receive timely security updates from the manufacturer
  • Block sideloading and enforce Google Play Protect on managed Android devices
bash
# Verify Android security patch level on a device via adb
adb shell getprop ro.build.version.security_patch
# Expected output for remediated devices: 2026-09-01 or later

Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.

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