The latest updates for Chrome 137 and Firefox 139, released on Tuesday, address four high-severity memory vulnerabilities, with two fixes in each browser.
Google's Chrome update resolves a use-after-free flaw in the Media component, identified as CVE-2025-5958, and a type confusion bug in the V8 JavaScript engine, tagged CVE-2025-5959. Both issues were reported by external security researchers.
Use-after-free vulnerabilities may be exploited for remote code execution, data corruption, or denial of service. In Chrome, these flaws can potentially allow attackers to escape the browser’s sandbox if paired with other system-level or privileged browser vulnerabilities.
The type confusion vulnerability in Chrome’s V8 engine poses serious risks, including information leaks, system compromise, and remote code execution. Google typically rewards such findings with payments up to $55,000, though the payout for CVE-2025-5959 has not been finalized. The researcher from Ant Group Light-Year Security Lab who discovered the use-after-free issue received a reward of $8,000.
Chrome version 137.0.7151.103/.104 is now being rolled out for Windows and macOS, while Linux users will receive version 137.0.7151.103.
Mozilla also released Firefox 139.0.4 on Tuesday, fixing two memory-related flaws. These include a memory corruption issue in the canvas surfaces component, listed as CVE-2025-49709, and an integer overflow vulnerability in the OrderedHashTable, which is used by the JavaScript engine, labeled CVE-2025-49710.
In addition, Mozilla issued new updates for Thunderbird to address a serious vulnerability that could trigger unauthorized file downloads. On Linux, this flaw could cause users’ storage to fill up with junk data. On Windows, it could potentially lead to credential leaks through SMB links.
According to Mozilla, the flaw involves specially crafted HTML emails that use mailbox:/// links to start automatic downloads of PDF files without any user prompt, even when auto-save is disabled. The vulnerability, tracked as CVE-2025-5986, can be triggered by simply viewing such emails in HTML mode. Although downloading the file does require user interaction, visual tricks can be used to hide the download mechanism.
This issue was addressed in Thunderbird versions 139.0.2 and 128.11.1.
Both Google and Mozilla recommend updating browsers and email clients promptly, even though there is currently no evidence that any of these vulnerabilities are being actively exploited.
Found this article interesting? Follow us on X(Twitter) ,Threads and FaceBook to read more exclusive content we post.
