Integer Underflow Vulnerability in Avast Windows Filtering Platform Stream Parser
CVE-2026-80303
Key Information:
What is CVE-2026-80303?
The Avast Windows Filtering Platform (WFP) stream parser contains an integer underflow vulnerability that can lead to denial of service by crashing the system. This occurs due to improper validation of input stream sizes against expected boundaries during length calculations for packet fragment reassembly. When the parser encounters specially crafted input, the length computation underflows, resulting in an allocation or buffer access issue with a dangerously large wrapped-around size value. This vulnerability can be exploited remotely through network traffic targeting filtered ports or locally via malicious data sent to the filtering interface, ultimately causing a kernel panic and system crash.
Affected Version(s)
Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate Windows 0
AVG Antivirus Free, AVG Internet Security, AVG Ultimate Windows 0
Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced Windows 0