CVE-2021-4102
Google Chromium V8 Use-After-Free Vulnerability
Description
CVE-2021-4102 is a high-severity use-after-free vulnerability in the V8 JavaScript engine of Google Chrome. The flaw allows a remote attacker to potentially exploit heap corruption via a crafted HTML page, which could lead to arbitrary code execution within the browser's renderer process. With a CVSS 3.1 score of 8.8 (HIGH) and an EPSS score of 5.46% (90.1st percentile), this Chrome V8 vulnerability has a notable exploitation probability. CISA has added CVE-2021-4102 to its Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. This vulnerability could affect multiple Chromium-based browsers including Google Chrome, Microsoft Edge, and Opera.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| chrome | < 96.0.4664.110 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://chromereleases.googleblog.com/2021/12/stable-channel-update-for-desktop_13.html(Release Notes, Vendor Advisory)
- https://crbug.com/1278387(Third Party Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-4102(US Government Resource)
Weakness Type
CWE-416: Use After Free
Use After Free in the Google Chrome V8 JavaScript engine occurs when the engine continues to reference a memory location after it has been freed during garbage collection or object lifecycle management. In V8, complex JavaScript execution and JIT compilation can create race conditions where object references outlive their allocated memory, allowing attackers to craft HTML pages that trigger heap corruption through dangling pointers to freed memory regions.
Learn more: CWE-416 — Use After Free
Impact Analysis
CVE-2021-4102 has a CVSS 3.1 score of 8.8 (HIGH), indicating a serious threat to users of Chromium-based browsers. The vulnerability is remotely exploitable over the network with low attack complexity and no authentication required, though user interaction is needed since the victim must visit a malicious web page. Confidentiality (High): successful exploitation can expose sensitive browser data including session tokens, stored credentials, and browsing history. Integrity (High): heap corruption through the use-after-free condition allows attackers to execute arbitrary code within the renderer process, potentially modifying browser state and user data. Availability (High): exploitation can crash the browser or lead to system instability. The EPSS score of 5.46% (90.1st percentile) indicates a notable probability of exploitation, and CISA has confirmed active attacks leveraging this vulnerability in the wild.
Exploit Maturity
CVE-2021-4102 is confirmed as actively exploited through its listing in the CISA Known Exploited Vulnerabilities catalog, with an accelerated remediation deadline of 2021-12-29. Google acknowledged awareness of reports that an exploit for CVE-2021-4102 existed in the wild at the time of disclosure in December 2021. The EPSS score of 5.46% (90.1st percentile) indicates a notable exploitation probability. While specific public exploit code has not been widely published, the confirmed in-the-wild exploitation and the typically high value of browser V8 use-after-free vulnerabilities in exploit chains suggest sophisticated threat actors are leveraging this flaw.
Remediation
- Apply updates per vendor instructions as mandated by CISA KEV. Update Google Chrome to version 96.0.4664.110 or later, which patches this V8 use-after-free vulnerability.
- Ensure all Chromium-based browsers in the environment (Microsoft Edge, Opera, Brave, and others) are also updated to versions incorporating the V8 fix, as this vulnerability affects the shared Chromium V8 engine.
- Enable automatic browser updates across the organization and verify that update policies are not blocking critical security patches.
- As an interim mitigation, consider enabling site isolation and strict site process isolation in Chrome to limit the impact of renderer process compromise.
- Monitor for indicators of compromise including unexpected browser crashes, unusual JavaScript execution patterns, and suspicious network connections originating from browser processes, which may indicate exploitation attempts or successful compromise.
Technical Details
CVE-2021-4102 is a use-after-free vulnerability in the V8 JavaScript engine used by Google Chrome prior to version 96.0.4664.110. The flaw occurs when V8 continues to use a pointer to a heap object after that memory has been freed, creating a dangling reference. An attacker can craft a malicious HTML page containing JavaScript that triggers specific V8 code paths causing the use-after-free condition, then manipulates heap layout to place attacker-controlled data in the freed memory region. The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) confirms that exploitation requires the victim to visit a malicious page (user interaction required) but is otherwise straightforward with no authentication needed. The underlying weakness, CWE-416 (Use After Free), is a common and highly exploitable vulnerability class in browser engines due to the complexity of JavaScript object lifecycle management and JIT compilation in V8.
Frequently Asked Questions
Is CVE-2021-4102 being actively exploited?
Yes. CVE-2021-4102 is listed in the CISA Known Exploited Vulnerabilities catalog, and Google has confirmed awareness of in-the-wild exploitation. The EPSS score of 5.46% (90.1st percentile) indicates a notable exploitation probability.
What products are affected by CVE-2021-4102?
CVE-2021-4102 affects Google Chrome prior to version 96.0.4664.110. Since the vulnerability is in the V8 JavaScript engine, other Chromium-based browsers such as Microsoft Edge, Opera, and Brave may also be affected if they use the vulnerable V8 version.
How do I fix CVE-2021-4102?
Update Google Chrome to version 96.0.4664.110 or later. Also update all other Chromium-based browsers in your environment. Enable automatic browser updates to ensure timely patching of future V8 vulnerabilities.
How severe is CVE-2021-4102?
CVE-2021-4102 has a CVSS 3.1 score of 8.8 (HIGH). While user interaction is required (visiting a malicious web page), the vulnerability allows heap corruption that can lead to arbitrary code execution. The 5.46% EPSS score places it in the 90.1st percentile of exploitation probability.
Need Help With Vulnerability Management?
Our security experts can help you prioritize and remediate vulnerabilities effectively.