CVE-2025-27071: Qualcomm Fastconnect Buffer Overflow Flaw

CVE-2025-27071 Overview

CVE-2025-27071 is a critical memory corruption vulnerability affecting Qualcomm Powerline Communication Firmware across a wide range of chipsets. The vulnerability exists in the firmware's file processing functionality, where improper buffer handling during specific file operations can lead to memory corruption. This flaw enables remote attackers to potentially execute arbitrary code, compromise device integrity, or cause system instability without requiring any user interaction or prior authentication.

Critical Impact

This vulnerability allows unauthenticated remote attackers to corrupt memory and potentially achieve arbitrary code execution on affected Qualcomm-based devices, including smartphones, wearables, and XR platforms.

Affected Products

• Qualcomm FastConnect 6800/6900/7800 Firmware
• Qualcomm Snapdragon 8 Gen 1, 865/865+/870 5G Mobile Platform Firmware
• Qualcomm Snapdragon XR2 5G Platform Firmware
• Qualcomm Snapdragon W5+ Gen 1 Wearable Platform Firmware
• Qualcomm Snapdragon X55 5G Modem-RF System Firmware
• Qualcomm QCA6391/QCA6426/QCA6436 Firmware
• Qualcomm WCN3620/WCN3660B/WCN3980/WCN3988 Firmware
• Qualcomm SXR2130/SXR2230P/SXR2250P Firmware

Discovery Timeline

• August 6, 2025 - CVE-2025-27071 published to NVD
• August 19, 2025 - Last updated in NVD database

Technical Details for CVE-2025-27071

Vulnerability Analysis

This vulnerability is classified under CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The flaw resides within the Powerline Communication (PLC) firmware component used across multiple Qualcomm chipset families. When the firmware processes specific files, it fails to properly validate the size of input data before copying it into a fixed-size memory buffer. This oversight allows malformed or oversized input to overflow the buffer boundaries, corrupting adjacent memory regions.

The vulnerability is particularly dangerous because it can be triggered remotely over a network connection without requiring any privileges or user interaction. Successful exploitation could allow an attacker to overwrite critical memory structures, hijack program execution flow, and ultimately execute arbitrary code at the firmware level. Given the privileged nature of firmware execution, this could lead to complete device compromise, persistent backdoor installation, or denial of service conditions.

Root Cause

The root cause of CVE-2025-27071 is insufficient bounds checking during buffer copy operations in the Powerline Communication firmware. When processing certain file types, the firmware allocates a fixed-size buffer but does not verify that incoming data fits within the allocated space. This allows attackers to craft malicious files that exceed buffer boundaries, triggering a classic buffer overflow condition. The lack of input validation at the firmware level means there are no higher-level protections to catch the overflow before memory corruption occurs.

Attack Vector

The attack can be executed remotely over the network without requiring authentication or user interaction. An attacker would craft a specially formatted file designed to trigger the vulnerable code path in the PLC firmware. When the target device processes this malicious file, the oversized data overflows the destination buffer, potentially overwriting return addresses, function pointers, or other critical memory structures. The attacker could leverage this primitive to redirect execution flow to attacker-controlled shellcode, achieving arbitrary code execution at the firmware level.

The attack is particularly impactful on mobile devices, wearables, and XR platforms using the affected Qualcomm chipsets, as firmware-level compromise can bypass operating system security controls and enable persistent device compromise.

Detection Methods for CVE-2025-27071

Indicators of Compromise

• Unexpected device crashes or reboots, particularly during network communication or file processing operations
• Anomalous memory consumption patterns in firmware or system processes
• Unusual network traffic patterns involving malformed or oversized data packets to PLC interfaces
• Firmware integrity check failures or unexpected firmware modifications

Detection Strategies

• Monitor system logs for crash dumps or memory corruption indicators in PLC-related firmware components
• Implement network intrusion detection rules to identify anomalous or malformed traffic targeting Powerline Communication interfaces
• Deploy endpoint detection solutions capable of monitoring firmware-level behavior and anomalies
• Regularly perform firmware integrity verification against known-good baselines

Monitoring Recommendations

• Enable verbose logging on affected devices to capture firmware-level events and errors
• Implement network traffic analysis to detect potential exploitation attempts targeting PLC functionality
• Monitor for unusual device behavior such as unexpected reboots, crashes, or performance degradation
• Establish baseline behavior patterns for affected devices to facilitate anomaly detection

How to Mitigate CVE-2025-27071

Immediate Actions Required

• Review your device inventory to identify all systems using affected Qualcomm chipsets and firmware
• Prioritize firmware updates for internet-facing or high-risk devices
• Apply available firmware patches from device manufacturers as soon as they become available
• Implement network segmentation to limit exposure of vulnerable devices

Patch Information

Qualcomm has addressed this vulnerability in their August 2025 Security Bulletin. Device manufacturers will need to integrate these firmware fixes and distribute updates to end users through their standard update channels. Organizations should monitor their device vendors for patch availability and apply updates promptly upon release.

For detailed patch information, refer to the Qualcomm Security Bulletin August 2025.

Workarounds

• Restrict network exposure of affected devices by placing them behind firewalls or on isolated network segments
• Disable or limit Powerline Communication functionality if not required for business operations
• Implement strict ingress filtering to block potentially malicious traffic from reaching vulnerable firmware components
• Monitor affected devices closely for signs of compromise until patches can be applied

# Network isolation example for affected devices
# Add firewall rules to restrict PLC traffic to vulnerable devices
iptables -A INPUT -p tcp --dport [PLC_PORT] -j DROP
iptables -A INPUT -p udp --dport [PLC_PORT] -j DROP