Qualcomm RTP Buffer Over-read (CVE-2025-21427): Silent Memory Leak Threatens Device Confidentiality

Introduction

A critical buffer over-read vulnerability, CVE-2025-21427, has emerged within Qualcomm's Data HLOS - LNX subsystem, threatening the confidentiality of millions of devices globally. This flaw silently leaks sensitive memory data when processing malicious RTP packets, potentially exposing encryption keys and authentication tokens without any user interaction or authentication.

Qualcomm, a global leader in semiconductor and telecommunications equipment, powers billions of devices worldwide through its Snapdragon processors. The pervasive nature of Qualcomm's technology amplifies the potential impact of this vulnerability, making it a significant concern for security professionals and organizations alike.

Technical Information

CVE-2025-21427 specifically involves improper validation of RTP packet headers within Qualcomm's Data HLOS - LNX component. The vulnerability is classified as a buffer over-read (CWE-126), triggered when the RTP packet parser fails to correctly validate the number of contributing sources (CSRC) specified in the packet header against the actual payload length.

When a malicious RTP packet declares more contributing sources than the payload can accommodate, the parser inadvertently reads beyond the allocated buffer boundary into adjacent memory regions. This improper memory access does not crash the process but silently leaks sensitive memory contents, enabling attackers to remotely extract confidential data such as cryptographic keys or authentication tokens.

The attack vector for this vulnerability is network-based, requiring no authentication or user interaction. Attackers can exploit this flaw by crafting and transmitting specially designed RTP packets to vulnerable devices. Due to the stealthy nature of the buffer over-read, exploitation leaves minimal forensic traces, complicating detection and response efforts.

Affected Systems and Versions

The following Qualcomm chipsets and components integrating the Data HLOS - LNX module are confirmed vulnerable:

• Snapdragon Mobile Platforms: Snapdragon 8 Gen 3, Snapdragon 4 Gen 1, Snapdragon 8+ Gen 2
• Wireless Modems: FastConnect 6900/7800, QMP1000, WCD9380/9385
• Automotive and IoT Solutions: Snapdragon X65 5G Modem-RF, QCA6391

Firmware versions prior to the July 2025 security patches across Android, Linux, and real-time operating system deployments are vulnerable. Users should verify their device firmware versions and promptly apply available updates from their respective OEMs.

Vendor Security History

Qualcomm has historically faced challenges with timely patch releases and high vulnerability density, particularly in modem firmware. Past vulnerabilities have highlighted significant gaps between internal fixes and public disclosures, often leaving devices exposed for extended periods. However, recent initiatives, including AI-driven vulnerability triage and expanded bug bounty programs, have significantly improved Qualcomm's security response capabilities, reducing vulnerability exposure and enhancing transparency.

References

• Qualcomm July 2025 Security Bulletin
• NVD Entry for CVE-2025-21427
• CWE-126 Buffer Over-read

Security professionals and organizations should remain vigilant, promptly applying patches and implementing recommended mitigations to safeguard against potential exploitation of CVE-2025-21427.

Source: This report was created using AI

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