Mozilla has released emergency security updates to fix a critical zero-day vulnerability exploited in the wild, impacting its Firefox web browser and Thunderbird email client. From a report: Tracked as CVE-2023-4863, the security flaw is caused by a heap buffer overflow in the WebP code library (libwebp), whose impact spans from crashes to arbitrary code execution. “Opening a malicious WebP image could lead to a heap buffer overflow in the content process. We are aware of this issue being exploited in other products in the wild,” Mozilla said in an advisory published on Tuesday. Mozilla addressed the exploited zero-day in Firefox 117.0.1, Firefox ESR 115.2.1, Firefox ESR 102.15.1, Thunderbird 102.15.1, and Thunderbird 115.2.2. Even though specific details regarding the WebP flaw’s exploitation in attacks remain undisclosed, this critical vulnerability is being abused in real-world scenarios.