CVE-2025-27031: Qualcomm Fastconnect 6700 UAF Vulnerability

CVE-2025-27031 Overview

CVE-2025-27031 is a use-after-free vulnerability [CWE-416] affecting a wide range of Qualcomm firmware components. The flaw occurs during processing of IOCTL commands when a buffer used in write loopback mode is accessed after being freed. A local authenticated attacker can trigger memory corruption to compromise confidentiality, integrity, and availability on the affected device. The vulnerability impacts FastConnect, Snapdragon compute platforms, WCD audio codecs, WSA smart speaker amplifiers, and multiple QCM/QCS embedded platforms. Qualcomm disclosed the issue in its June 2025 security bulletin.

Critical Impact
A local, low-privileged attacker can trigger kernel-level memory corruption through crafted IOCTL commands, enabling arbitrary code execution and full device compromise.

Affected Products

Qualcomm FastConnect 6700, 6900, and 7800 firmware
Qualcomm Snapdragon 7c+ Gen 3 Compute and 8cx Gen 3 Compute Platform (SC8280XP-AB/BB) firmware
Qualcomm WCD9370/9375/9380/9385, WSA8830/8835/8840/8845/8845H, QCM/QCS 5430/6490, SC8380XP, and Video Collaboration VC3 Platform firmware

Discovery Timeline

2025-06-03 - CVE-2025-27031 published to NVD
June 2025 - Qualcomm publishes fix in Qualcomm Security Bulletin June 2025
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-27031

Vulnerability Analysis

The vulnerability is a use-after-free condition [CWE-416] in the IOCTL command handler responsible for write loopback mode operations. When the driver processes specific IOCTL requests, a buffer used to stage loopback write data is freed while a reference to it remains reachable. Subsequent code paths dereference the stale pointer, resulting in memory corruption inside kernel or privileged driver context.

Exploitation requires local access with low privileges but no user interaction. Successful exploitation grants an attacker the ability to influence kernel memory contents, corrupt adjacent structures, or hijack control flow. The scope remains unchanged, meaning corruption is confined to the affected component's security context, which on these platforms is typically the kernel or a privileged firmware service.

Root Cause

The root cause is improper lifecycle management of a heap-allocated buffer used during IOCTL-driven write loopback operations. The driver releases the buffer before all code paths that reference it have completed. No sanity check confirms the buffer is still valid before subsequent access, allowing the freed allocation to be reclaimed and repurposed by an attacker-controlled allocation.

Attack Vector

An unprivileged local process on an affected device opens the vulnerable driver's device node and issues a sequence of IOCTL commands that place the driver into write loopback mode. By timing a follow-up IOCTL to reach the vulnerable code path after the buffer has been freed, the attacker forces access to the dangling pointer. Heap grooming techniques can be used to replace the freed allocation with attacker-controlled data before the reuse occurs, converting the use-after-free into arbitrary read, write, or code execution.

No public proof-of-concept exploit or CISA Known Exploited Vulnerabilities listing exists at the time of writing. See the Qualcomm Security Bulletin June 2025 for vendor technical details.

Detection Methods for CVE-2025-27031

Indicators of Compromise

Unexpected kernel panics, driver crashes, or system reboots referencing Qualcomm audio, Wi-Fi, or platform drivers involved in loopback IOCTL paths
Unprivileged processes opening Qualcomm driver device nodes and issuing high-frequency IOCTL sequences targeting loopback functionality
Anomalous kernel memory corruption traces or KASAN use-after-free reports on affected Snapdragon-based devices

Detection Strategies

Monitor endpoint telemetry for local processes that open Qualcomm platform driver device files and issue rapid IOCTL sequences from non-system UIDs
Correlate kernel crash dumps and dmesg output with process activity to identify use-after-free triggers tied to loopback command codes
Track privilege transitions immediately following interaction with affected drivers as an indicator of successful exploitation

Monitoring Recommendations

Enable kernel-level logging (including KASAN or vendor-equivalent instrumentation) on test and QA fleets to catch exploitation attempts early
Aggregate driver crash telemetry into a central data lake and alert on repeated crashes from the same process or device model
Baseline normal IOCTL patterns for Qualcomm drivers so deviations can be surfaced as high-signal alerts

How to Mitigate CVE-2025-27031

Immediate Actions Required

Inventory devices using affected Qualcomm chipsets, including FastConnect, Snapdragon 7c+/8cx Gen 3 Compute, WCD, WSA, QCM, and QCS parts
Apply the OEM firmware update that incorporates Qualcomm's June 2025 patch as soon as it is available for each device model
Restrict local access on multi-user or shared devices until patched firmware is deployed

Patch Information

Qualcomm addressed the use-after-free in the June 2025 security bulletin. Device OEMs must integrate the fix into their firmware and ship updates to end users. Consult the Qualcomm Security Bulletin June 2025 for the authoritative list of fixed components and version identifiers, then track each OEM's downstream release notes for delivery timing.

Workarounds

Limit which local users and applications can access affected Qualcomm driver device nodes using OS-level access controls where supported
Disable or avoid use of write loopback functionality in affected components if the platform exposes a configuration option
Reduce attack surface by removing untrusted third-party applications on devices that cannot yet receive patched firmware

bash

# Example: restrict access to a Qualcomm driver device node on Linux-based platforms
# Replace /dev/qcom_example with the actual device node exposed by the affected driver
sudo chown root:root /dev/qcom_example
sudo chmod 600 /dev/qcom_example