Chrome V8 Engine JavaScript Interpreter Vulnerability

漏洞信息

漏洞名称： Chrome V8 Engine JavaScript Interpreter Vulnerability

漏洞编号：

• CVE： CVE-2025-6554

漏洞类型： 代码注入

漏洞等级： 高危

漏洞描述： CVE-2025-6554是Chrome V8 JavaScript引擎中的一个漏洞，涉及在可选链表达式中对未初始化变量的不充分控制。该漏洞允许读取通常被引用阻止的非初始化值行为。具体来说，漏洞存在于V8引擎的“Hole”验证机制中，该机制在变量使用前未能正确验证其初始化状态，导致可以在变量声明前访问其值。

受影响产品: Chrome V8引擎是Google Chrome浏览器的JavaScript执行引擎，广泛用于现代Web应用程序中，提供高性能的JavaScript执行能力。由于其广泛的应用，该漏洞的影响范围较大。

漏洞解释: 此漏洞属于代码注入类型，根源在于V8引擎在处理可选链表达式时，对未初始化变量的控制不足。特别是在变量声明前访问变量时，引擎未能正确抛出引用错误，导致可以捕获到特殊的“Hole”值。这种机制的错误允许攻击者推断V8引擎的内部状态，进而可能进行类型混淆、堆栈操纵等攻击。

影响分析: 该漏洞为攻击者提供了对V8引擎内部状态的访问能力，可能导致类型混淆、堆栈操纵等严重安全问题。由于V8引擎在Chrome浏览器中的核心地位，利用此漏洞可能导致远程代码执行、数据泄露等高风险后果。攻击者无需认证即可利用此漏洞，且可以自动化执行，增加了其潜在危害。

产品厂商： Google

产品名称： Chrome V8 Engine

来源： https://github.com/ghostn4444/POC-CVE-2025-6554

类型： CVE-2025:github search

仓库文件

• Exploit.js
• README.md
• Test-Exploit.js

来源概述

CVE-2025-6554

CVE-2025-6554 is a vulnerability in Chrome’s V8 (Engine JavaScript) interpreter (Hole Check ‘inadequate control in unintended variables within expressions with optional chaining. POC (CVE-2025-6554-POC.JS) explores a flaw in the “Hole” verification mechanism in variables before use, allowing non-initialized values ​​reading-behavior that is normally blocked by a reference.

function leak_hole() {
    let x;
    delete x?.[y]?.a;
    return y;
    let y;
}
function pwn() {
    let hole = leak_hole();
    %DebugPrint(hole);
}
pwn();

---

Technical Explanation

1. Structure of the Vulnerable Code

Let x; and let y; declare local scope variables.
The Delete X line?. [Y]?. Use optional chaining to access a nestled property safely.
Problem: Variable Y is used before it was declared, which should launch a referencing, but in the pre-coordination V8, this failed silently, allowing it to capture the special value called “The Hole” (sentinel for TDZ variables-Dead Zone Temporal).
The return value (return Y) in the code should not be accessible because Y is still in TDZ. But the failure allows it.

2. Behavior before patch

The mechanism that avoids access to variables in TDZ is ThrowReferenceerrofhole.
Before the patch, this mechanism was invoked only once during Delete X?. [Y]?
The V8 internally marked that variable Y had already been verified as “not being a hole”, but this verification was escaping from the controlled scope, and therefore was not reevaluated during the return y.

3. What was corrected

The patch adds another mandatory call to ThrowReferenceerrorifhole on return Y, ensuring that any attempt to access Y before the statement correctly fires a mistake.
This verification was guaranteed by the scope oilchecketscope, which was included in all calls to optionalchainnulllabelscope.

attack flow

Delete x?. [Y]?. → Try to access Y (not initialized) → Failure to check "Hole" 
→ Y escapes as value → return y; → Capture the value of "Hole" → Debugprint reveals

The attacker, when capturing this “Hole”, can infer on the inner state of Engine V8, facilitating attacks such as:

• Type Exploration Confusion

• Stack Manipulation

• Scope check circumstance