CVE-2026-56997 in Android
Summary
by MITRE • 09/15/2026
In Av1DecodeFrameTag of vp9hwd_headers.cc, there is a possible out-of-bounds write due to a missing bounds check. This could lead to remote escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified in the Av1DecodeFrameTag function within vp9hwd_headers.cc represents a critical memory safety issue characterized by an out-of-bounds write condition. This flaw stems from a fundamental failure to perform adequate bounds checking on input data during the parsing of VP9 or AV1 video stream headers. In modern web browsers and media processing libraries, header decoding is often performed in privileged contexts with high-level access to system resources. When the decoder processes malformed or specifically crafted bitstream data that exceeds expected limits for frame tags or header structures, the absence of validation allows the application to write memory locations outside the allocated buffer boundaries. This type of error falls squarely under CWE-787, which defines out-of-bounds writes as a category where software accesses memory beyond the intended boundary, potentially overwriting adjacent data structures and corrupting program state.
The operational impact of this vulnerability is severe due to its potential for remote code execution and privilege escalation. Because the flaw exists in a core media decoding component, it can be triggered simply by loading a maliciously crafted video file or stream within a web page or application that utilizes the underlying library. The description indicates that user interaction is not required beyond initial exposure to the content, which significantly lowers the barrier for exploitation. Attackers do not need additional execution privileges on the target system to leverage this flaw; instead, they can exploit it through standard network vectors such as HTTP requests embedding malicious media payloads or via phishing campaigns delivering infected files. The ability to write arbitrary data to memory locations outside of allocated buffers enables attackers to overwrite critical control flow data, function pointers, or return addresses, thereby gaining the ability to execute arbitrary code within the context of the vulnerable process.
From a threat intelligence perspective, this vulnerability aligns with ATT&CK techniques related to initial access and execution through media content. Specifically, it relates to T1204 User Execution if triggered by opening a file, or more commonly in browser contexts, T1189 Drive-by Compromise where the exploitation occurs automatically upon visiting a malicious website. The lack of required user interaction beyond viewing the page makes this particularly dangerous for public-facing web services and applications that render video content dynamically. The potential for remote escalation of privilege suggests that if the vulnerable process runs with elevated permissions, such as in certain enterprise environments or sandboxed containers with specific configurations, an attacker could break out of restricted execution contexts to gain broader system access.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Developers should immediately apply vendor-provided patches that introduce rigorous bounds checking within the Av1DecodeFrameTag function to ensure all memory accesses remain within allocated limits during header parsing. Input validation mechanisms must be strengthened to reject any bitstream data that violates structural constraints defined by the AV1 or VP9 specifications. For system administrators, deploying Web Application Firewalls with deep packet inspection capabilities can help detect and block requests containing malformed media headers before they reach the vulnerable decoding engine. Additionally, enabling memory protection features such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) can mitigate the impact of successful exploitation by making it harder for attackers to predict target addresses or execute injected code. Regular security audits focusing on C++ memory management practices are essential to prevent similar out-of-bounds errors in other parts of the media processing pipeline.