CVE-2025-21006 in libsavsvc.so
Summary
by MITRE • 07/08/2025
Out-of-bounds write in handling of macro blocks for MPEG4 codec in libsavsvc.so prior to Android 15 allows local attackers to write out-of-bounds memory.
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Analysis
by VulDB Data Team • 07/08/2025
The vulnerability identified as CVE-2025-21006 represents a critical out-of-bounds write flaw within the MPEG4 codec implementation in the libsavsvc.so library affecting Android versions prior to Android 15. This issue resides in the handling of macro blocks during video processing operations, where insufficient input validation leads to memory corruption. The vulnerability specifically impacts the multimedia framework's video decoding capabilities and manifests when processing malformed MPEG4 video streams or files containing crafted macro block data structures. The out-of-bounds write condition occurs due to improper bounds checking during the parsing and rendering of macro block information within the codec's processing pipeline, potentially allowing attackers to overwrite adjacent memory locations with arbitrary data.
Security implications of this vulnerability extend beyond simple memory corruption as it provides local attackers with a potential pathway for privilege escalation and system compromise. The flaw exists within a system-level library that handles multimedia processing, making it particularly dangerous as it can be exploited through various attack vectors including malicious video files, web content, or applications that utilize the affected codec. The vulnerability aligns with CWE-787 Out-of-bounds Write, which specifically addresses writing to memory locations beyond the bounds of allocated buffers, and demonstrates characteristics consistent with CWE-129 Improper Validation of Array Index. From an operational perspective, this vulnerability creates opportunities for attackers to execute arbitrary code within the context of the multimedia processing service, potentially leading to complete system compromise.
The attack surface for CVE-2025-21006 encompasses any Android device running versions prior to Android 15 that processes MPEG4 video content through the affected libsavsvc.so library. This includes mobile devices, tablets, and other embedded systems that utilize the Android multimedia framework for video playback and processing. The vulnerability is particularly concerning as it requires no special privileges to exploit, making it accessible to local attackers who can manipulate video content or trigger processing of malicious media files. The impact of exploitation could range from denial of service conditions to full system compromise, depending on the specific memory locations overwritten and the privileges of the affected process. Attackers could leverage this vulnerability through techniques such as buffer overflow exploitation, memory corruption, or code injection methods that take advantage of the out-of-bounds write condition.
Mitigation strategies for this vulnerability should focus on immediate patch deployment for Android 15 and subsequent versions where the fix has been implemented. Organizations should prioritize updating their Android devices and applications to versions that contain the patched libsavsvc.so library, as the vulnerability affects core system components that are difficult to isolate or protect through traditional network security measures. System administrators should also implement monitoring for unusual video processing behavior or memory allocation patterns that could indicate exploitation attempts. The remediation approach aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: JavaScript, where attackers might attempt to exploit such vulnerabilities through media-based attack vectors. Additionally, implementing strict input validation and bounds checking within multimedia processing applications can provide defense-in-depth measures. The vulnerability serves as a reminder of the importance of regular security updates and proper input validation in multimedia processing components, particularly those handling complex codec implementations that process untrusted data from various sources.