CVE-2026-121049 in Chrome
Summary
by MITRE • 11/03/2026
Out of bounds read in V8 in Google Chrome prior to 157.0.8103.38 allowed a local attacker to read memory via a crafted file. (Chromium security severity: Medium)
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an out-of-bounds read within the V8 JavaScript engine, which powers Google Chrome prior to version 157.0.8103.38, represents a critical memory safety flaw that undermines the integrity of data processing during script execution. This type of error occurs when the application attempts to access memory locations beyond the boundaries of an allocated buffer or array structure. In the context of V8, this typically involves JavaScript objects where index calculations are not properly validated against the actual size of underlying arrays or typed buffers. When a crafted file is processed by the browser, it may trigger specific parsing routines that execute maliciously constructed scripts containing these invalid memory access patterns. The severity of this issue is classified as medium within the Chromium security framework because while it allows for information disclosure rather than direct code execution, it serves as a potent primitive for further exploitation chains in modern web environments.
From a technical perspective, out-of-bounds reads are categorized under CWE-125, which describes an operation that attempts to read data from outside the bounds of a buffer or array. This flaw arises due to insufficient validation checks on input parameters before they are used as indices for memory access operations. In V8, such errors can be triggered through complex interactions between JavaScript code and native C++ components during garbage collection cycles or just-in-time compilation processes. An attacker who crafts a file with specific binary structures or embedded scripts can manipulate these internal states to force the engine into reading arbitrary memory addresses. This capability allows for the leakage of sensitive information stored in adjacent memory regions, such as pointers to other objects, cryptographic keys, or session tokens that reside within the browser process space.
The operational impact of this vulnerability centers on unauthorized data exfiltration and potential reconnaissance activities against the victim system. Although classified as a local attack vector due to the requirement for user interaction via opening a crafted file, the implications extend beyond simple memory leakage. By carefully analyzing the leaked memory contents, an attacker can perform heap spraying techniques or gather information about the browser's internal state, which significantly lowers the barrier for subsequent attacks such as arbitrary code execution through use-after-free exploits or type confusion vulnerabilities. This aligns with ATT&CK technique T1074, Data Staged, where data is collected and stored locally before exfiltration, although in this specific case, the primary goal remains information gathering rather than persistent staging. The ability to read memory also facilitates bypassing security mitigations like ASLR by leaking pointer addresses that reveal base load addresses of critical libraries.
Mitigation strategies for this vulnerability primarily involve updating the browser software to version 157.0.8103.38 or later, where Google has implemented stricter bounds checking and improved validation logic within V8's array handling routines. For organizations managing large fleets of endpoints, automated patch management systems should be configured to prioritize updates for browsers containing known memory safety vulnerabilities. Additionally, users can reduce their exposure by disabling JavaScript execution in untrusted environments using browser security settings or extensions that restrict script capabilities on specific domains. Implementing strict content security policies and ensuring that file downloads from unknown sources are scanned with advanced endpoint detection tools can further mitigate the risk of triggering such exploits through crafted files. Regular auditing of third-party plugins and extensions is also recommended, as they may interact with V8 in ways that exacerbate these memory safety issues if not properly sandboxed or updated.