CVE-2026-87639 in Chrome
Summary
by MITRE • 09/09/2026
Use after free in WebPackaging in Google Chrome prior to 153.0.8010.36 allowed a remote attacker who had compromised the renderer process to potentially execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as a use-after-free condition within WebPackaging in Google Chrome prior to version 153.0.8010.36 represents a critical memory management flaw that undermines the browser's sandboxing architecture. Use-after-free vulnerabilities occur when a program continues to use a pointer after the memory it points to has been freed, leading to undefined behavior that can be exploited by malicious actors. In this specific instance, the defect resides in the WebPackaging component, which is responsible for handling web package files used for offline applications and progressive web apps. The flaw allows an attacker who has already compromised the renderer process through a separate initial vector or exploit chain to escalate privileges beyond the restricted sandbox environment. This escalation is significant because modern browsers rely heavily on sandboxes to isolate untrusted content from sensitive system resources, ensuring that even if one tab is compromised, the rest of the user's data and operating system remain protected.
From a technical perspective, the exploitation of this vulnerability likely involves manipulating object lifecycles within the WebPackaging module such that memory previously allocated for an object is deallocated but still referenced by another part of the application. When the renderer process attempts to access or modify this dangling pointer, it may trigger arbitrary code execution in the context of a higher-privilege process or bypass sandbox boundaries entirely. This scenario aligns with CWE-416, which classifies use-after-free errors as a distinct category of memory corruption vulnerabilities. The ability for an attacker to execute arbitrary code outside the sandbox effectively neutralizes one of the most important security controls in modern web browsers, allowing full control over the underlying operating system if successful exploitation occurs without additional mitigations like DEP or ASLR being bypassed by other means.
The operational impact of this vulnerability is severe, particularly given its classification as a High severity issue within the Chromium project. An attacker could craft a malicious HTML page that triggers the use-after-free condition when processed by Chrome's WebPackaging subsystem. If successful, this would allow remote code execution with elevated privileges, potentially leading to complete system compromise. This includes the ability to install malware, steal sensitive data such as credentials and cookies stored in browser profiles, or pivot further into internal networks if the user is part of a corporate environment. The risk is amplified by the fact that it requires only a crafted web page, making it feasible for drive-by download attacks where users are tricked into visiting malicious sites without any additional interaction beyond loading the page.
In terms of threat modeling and attack patterns, this vulnerability maps to MITRE ATT&CK techniques related to privilege escalation and sandbox escape. Specifically, it relates to tactics involving execution on remote systems and defense evasion by bypassing browser security features. Security teams should prioritize patching Chrome to version 153.0.8010.36 or later immediately upon availability. Additionally, organizations can mitigate risks by enforcing strict content security policies, disabling unnecessary web packaging features if not required for business operations, and ensuring that endpoint detection and response solutions are active to detect anomalous behavior resulting from potential exploitation attempts. Regular updates of all browser components remain the primary defense against such memory corruption vulnerabilities, as they often stem from complex interactions between different modules within large codebases like Chromium.