Chromium Use-After-Free Vulnerability in Cast (CVE-2026-7338)

CVE-2026-7338 is a critical use-after-free vulnerability residing within the Cast component of the Chromium browser engine. Google Chrome and Microsoft Edge (Chromium-based) are both affected by this flaw. While the provided source does not specify the exact vulnerable versions, it indicates that Microsoft Edge ingests Chromium, and thus is affected by vulnerabilities addressed in Chromium releases. Successful exploitation of this vulnerability could lead to arbitrary code execution in the context of the user running the browser. This poses a significant risk, as attackers could potentially gain control of the user’s system. Defenders should prioritize patching affected browsers.

Attack Chain

1. An attacker crafts a malicious webpage or injects malicious code into a legitimate website that utilizes the Cast functionality.
2. The victim visits the malicious website or interacts with the compromised legitimate website using an affected browser (Chrome or Edge).
3. The malicious webpage triggers the use-after-free vulnerability in the Cast component.
4. The vulnerability allows the attacker to access memory that has already been freed.
5. The attacker overwrites the freed memory with attacker-controlled data.
6. The attacker manipulates the memory layout to redirect program execution.
7. The browser attempts to execute code from the attacker-controlled memory location.
8. This results in arbitrary code execution within the context of the browser process.

Impact

Successful exploitation of CVE-2026-7338 allows an attacker to execute arbitrary code on a victim’s machine. This can lead to complete system compromise, data theft, installation of malware, or other malicious activities. Given the widespread use of Chromium-based browsers like Chrome and Edge, this vulnerability has the potential to impact a large number of users across various sectors. The severity is critical due to the potential for remote code execution.

Recommendation

• Apply the latest security updates for Google Chrome to address CVE-2026-7338 as detailed in Google Chrome Releases.
• Apply the latest security updates for Microsoft Edge (Chromium-based) to address CVE-2026-7338, ensuring the ingested Chromium version contains the fix.
• Deploy the Sigma rules provided in this brief to your SIEM to detect potential exploitation attempts targeting the Cast component.
• Enable enhanced browser security features, such as sandboxing and site isolation, to limit the impact of potential exploits.