CVE-2025-21426: Qualcomm Fastconnect 7800 Buffer Overflow

CVE-2025-21426 Overview

CVE-2025-21426 is a memory corruption vulnerability in Qualcomm firmware affecting the camera Test Pattern Generator (TPG) subsystem. The flaw occurs during processing of write requests to the camera TPG driver. A local attacker with low privileges can trigger the condition to corrupt kernel memory. Successful exploitation impacts confidentiality, integrity, and availability on affected Snapdragon and FastConnect platforms. The vulnerability is classified under [CWE-120] Buffer Copy without Checking Size of Input. Qualcomm addressed the issue in the Qualcomm Security Bulletin July 2025.

Critical Impact
Local attackers can corrupt kernel memory through the camera TPG interface, enabling privilege escalation or denial of service on affected Qualcomm chipsets used in mobile and XR devices.

Affected Products

Qualcomm FastConnect 7800 firmware
Qualcomm Snapdragon AR1 Gen 1 Platform firmware
Qualcomm SSG2115P, SSG2125P, SXR1230P firmware

Discovery Timeline

2025-07-08 - CVE-2025-21426 published to NVD following the Qualcomm July 2025 Security Bulletin
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-21426

Vulnerability Analysis

The vulnerability resides in the Qualcomm camera driver stack, specifically the Test Pattern Generator (TPG) write request handler. The TPG component generates synthetic image data used to validate camera pipelines during development and diagnostics. When the driver processes a write request from userspace, insufficient validation of input size or bounds allows memory corruption in kernel context. Exploitation requires local access with low privileges, meaning a malicious application on the device can invoke the vulnerable ioctl path. Successful exploitation can lead to arbitrary kernel memory writes, resulting in privilege escalation, kernel panic, or persistent device compromise.

Root Cause

The root cause is classified as [CWE-120] Buffer Copy without Checking Size of Input, commonly known as a classic buffer overflow. The TPG write request handler copies attacker-controlled data into a fixed-size kernel buffer without validating the length of the incoming payload. Because the copy operates in kernel address space, overflow bytes overwrite adjacent kernel structures or function pointers.

Attack Vector

An unprivileged local application interacts with the camera TPG device node exposed by the vulnerable Qualcomm driver. The attacker crafts a malformed write request containing oversized or malformed parameters. The driver accepts the request and performs the unchecked copy, corrupting kernel memory. No user interaction is required beyond executing the malicious application. See the Qualcomm Security Bulletin July 2025 for technical acknowledgments.

// No verified public proof-of-concept is available.
// See vendor advisory for driver-level technical details.

Detection Methods for CVE-2025-21426

Indicators of Compromise

Unexpected kernel panics or reboots referencing the camera TPG driver in bootloader or kernel logs.
Presence of unknown applications interacting with camera device nodes such as /dev/v4l-subdev* or Qualcomm-specific camera ioctl interfaces.
Anomalous SELinux denials tied to camera subsystem access from non-camera applications.

Detection Strategies

Monitor Android and XR device logs (logcat, dmesg) for camera driver faults, TPG-related error strings, or memory access violations in kernel context.
Inventory OEM firmware builds and correlate against the Qualcomm July 2025 Security Bulletin patch level to identify unpatched devices.
Deploy mobile application vetting to identify apps requesting camera hardware access without a legitimate use case.

Monitoring Recommendations

Enable centralized collection of mobile device telemetry, including kernel crash reports and patch level attestation.
Track application installations that request android.permission.CAMERA alongside native code execution capabilities.
Alert on repeated device crashes across a fleet, which may indicate exploitation attempts against camera drivers.

How to Mitigate CVE-2025-21426

Immediate Actions Required

Apply the July 2025 Qualcomm firmware update through OEM device patches as soon as they become available for your device model.
Verify device security patch level reflects the July 2025 Android Security Bulletin or later.
Restrict installation of untrusted third-party applications on affected mobile and XR devices.

Patch Information

Qualcomm released fixes as part of the July 2025 Security Bulletin. Original Equipment Manufacturers (OEMs) integrate these patches into device firmware updates. Refer to the Qualcomm Security Bulletin July 2025 and consult your device vendor for the corresponding firmware release.

Workarounds

No official vendor workaround has been published; patching remains the required remediation path.
Enforce mobile device management (MDM) policies that block sideloading and restrict camera access to trusted applications.
Where feasible, disable or remove diagnostic and camera testing applications that expose the TPG interface to userspace.

bash

# Verify Android security patch level on an affected device
adb shell getprop ro.build.version.security_patch

# Enumerate camera-related device nodes for auditing
adb shell ls -la /dev/v4l-subdev* /dev/video*