Introduction
Remote code execution through a single malicious image remains one of the most impactful threats to mobile device security. CVE-2025-21043, a high-severity out-of-bounds write in Samsung's Quram image codec library, exposes millions of Samsung Android devices to arbitrary code execution prior to the September 2025 Security Maintenance Release.
About Samsung and Quram: Samsung is the largest global smartphone vendor, shipping hundreds of millions of Android devices yearly. Its proprietary Quram image codec, integrated since Android 4.4.4, handles custom image formats and is deeply embedded in the graphics subsystem. Vulnerabilities in this codec have repeatedly enabled remote exploitation via MMS, email, and web content, making them highly relevant to both attackers and defenders.
Technical Information
CVE-2025-21043 is an out-of-bounds write vulnerability in libimagecodec.quram.so, a core shared object in Samsung's image processing stack. The vulnerability is triggered during the parsing of specially crafted image files, allowing attacker-controlled data to overwrite memory outside of allocated buffers. This can lead to remote code execution in the context of the image processing service or application.
The Quram codec is known for its complex, memory-unsafe C codebase. Previous research by Google Project Zero (see Project Zero analysis) identified large functions with minimal bounds checking and a history of buffer overflows. While the exact vulnerable function for CVE-2025-21043 is not public, the pattern matches prior vulnerabilities where image metadata or decompression routines failed to validate input sizes, allowing out-of-bounds writes.
The vulnerability is remotely exploitable. Attackers can deliver malicious images through MMS, email attachments, or web content. No user interaction is required beyond the device processing the image, which can occur automatically in some messaging or preview scenarios. This attack surface is significant due to the codec's integration with Android's Skia graphics library and automatic image handling by system services.
No public code snippets or proof of concept are available for this issue. The vulnerability was addressed by Samsung in the September 2025 SMR.
Affected Systems and Versions
- Products: Samsung Android smartphones, tablets, and devices using Quram image codec
- Component:
libimagecodec.quram.so - Version range: All Samsung devices with Quram image codec prior to September 2025 Security Maintenance Release 1
- Configurations: Devices running Samsung's proprietary Android builds with Quram integration (typically all Galaxy series and related models)
Vendor Security History
Samsung has a documented history of critical vulnerabilities in its Quram image codec:
- CVE-2020-8899: Zero-click MMS remote code execution, affecting all Samsung devices since 2014
- CVE-2021-25346: Information disclosure in Quram ImageCodec
Samsung's patch response time has improved, with monthly security updates and a five-year support policy for flagship devices. However, recurring memory safety issues in proprietary components like Quram remain a persistent risk.