CVE-2026-0878

CVE-2026-0878 is a high-severity sandbox escape vulnerability affecting Mozilla Firefox and Thunderbird versions prior to 147 and 140.7 respectively, stemming from incorrect boundary conditions in the Graphics: CanvasWebGL component. This vulnerability has a CVSS score of 8.0 (High), indicating a network-based attack requiring user interaction and high attack complexity, but with the potential for high confidentiality and integrity impact. While there is no evidence of active exploitation, nor publicly available exploit code in Metasploit or ExploitDB, the vulnerability has garnered significant community discussion with 10 mentions, suggesting a degree of awareness and interest.