CVE-2026-121208 in Chrome
Summary
by MITRE • 11/03/2026
Out of bounds read in Media in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to potentially execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an out-of-bounds read within the Media component of Google Chrome prior to version 157.0.8103.38 represents a critical memory safety flaw that undermines the browser's sandboxing mechanisms. This type of error occurs when software attempts to access data at a memory location beyond the intended boundaries, typically due to improper validation of array indices or pointer arithmetic during media processing operations. In the context of web browsers, such flaws are particularly dangerous because they can be triggered by maliciously crafted content embedded in standard HTML pages. The attacker leverages this flaw to read sensitive information from adjacent memory regions that should remain inaccessible to untrusted code, potentially leading to further exploitation steps or direct compromise depending on how the leaked data is utilized.
From a technical perspective, the Media component handles various multimedia formats and codecs, which are complex subsystems often written in lower-level languages like C++ where manual memory management is prevalent. The specific flaw likely stems from insufficient checks when parsing media streams or decoding video/audio data structures. When a crafted HTML page triggers this code path with specially constructed inputs, the application fails to verify that the read operation stays within allocated buffers. This results in an out-of-bounds read condition classified under CWE-125: Out-of-bounds Read. The severity is rated as High by Chromium because while it starts as a memory disclosure issue, such vulnerabilities are frequently chained with other techniques to achieve arbitrary code execution. By carefully controlling the data layout and exploiting the side effects of reading out-of-bounds memory, an attacker can manipulate control flow or overwrite critical pointers, thereby bypassing browser sandbox restrictions.
The operational impact of this vulnerability is severe for end-users who browse the web using affected versions of Chrome. A remote attacker does not need physical access or prior authentication; they simply need to host a malicious webpage and lure a victim into visiting it via phishing links, compromised advertisements, or drive-by download tactics. Once executed within the browser's sandboxed environment, the exploit can potentially escape this isolation layer. If successful in achieving arbitrary code execution inside the sandbox, the attacker gains significant privileges relative to other processes on the system. This could lead to data theft, installation of malware, or use of the compromised machine as part of a botnet. The ability to execute code within the sandbox significantly lowers the barrier for exploitation compared to vulnerabilities that remain confined strictly to memory disclosure without further escalation paths.
To mitigate this risk, organizations and individual users must ensure that Google Chrome is updated to version 157.0.8103.38 or later immediately upon availability. This update contains patches that enforce stricter bounds checking within the media processing logic, preventing the out-of-bounds access from occurring in the first place. Additionally, defense-in-depth strategies should be employed, including keeping operating systems and other browser plugins up to date to minimize the attack surface. Security teams can also monitor for indicators of compromise related to unusual memory usage patterns or network connections originating from browser processes, which may signal active exploitation attempts. Regular security audits focusing on input validation in multimedia handling components are recommended to prevent similar issues in future software releases. The remediation aligns with standard vulnerability management practices and addresses the specific technical flaw described without requiring architectural changes beyond patching the identified code defect.