Google on Monday released an emergency Chrome 116 security update to patch the fourth zero-day vulnerability discovered in the browser in 2023.
Tracked as CVE-2023-4863 and rated ‘critical severity’, the bug is described as a heap buffer overflow issue in the WebP component.
WebP is an image format that provides improved compression and quality compared to the well-known JPEG and PNG formats, and which is supported by all modern browsers, including Chrome, Firefox, Safari, Edge, and Opera.
“Google is aware that an exploit for CVE-2023-4863 exists in the wild,” the internet giant notes in an advisory.
According to Google, the vulnerability was reported on September 6 by Apple Security Engineering and Architecture (SEAR) and The Citizen Lab at The University of Torontoʼs Munk School, which often exposes the activities of commercial spyware vendors. Per the internet giant’s policy, no bug bounty will be handed out for the flaw.
Heap buffer overflow issues occur when an application writes more data to a heap-allocated memory buffer than what the buffer can hold. Such vulnerabilities can be exploited to crash an application and potentially achieve arbitrary code execution.
As usual, Google has refrained from disclosing details on the bug. The company does not provide information on the observed exploitation either.
However, the fact that SEAR and Citizen Lab were credited for the finding may indicate that the vulnerability has been exploited by a commercial spyware vendor, which typically claim to help government agencies conduct lawful surveillance.
Products offered by these spyware vendors, however, often target Android users with complex exploit chains that often also integrate Chrome exploits.
Google’s Chrome patch comes just days after Apple announced fixing zero-days in iOS and macOS. Citizen Lab discovered the Apple product flaws during the analysis of exploitation activity linked to NSO Group’s Pegasus mercenary spyware.
CVE-2023-4863 is the fourth zero-day vulnerability that Google has patched in Chrome this year, after addressing CVE-2023-3079 (type confusion in the V8 engine) in June, and CVE-2023-2033 (type confusion in the V8 engine) and CVE-2023-2136 (integer overflow in Skia) in April.
The latest Chrome iteration is now rolling out to users as version 116.0.5845.187 for macOS and Linux, and as versions 116.0.5845.187/.188 for Windows.