Answer in brief
CVE-2026-80303 records a Unknown severity vulnerability in Avast WFP stream parser integer underflow causes system crash. The current sources do not mark it as known exploited. The current feed maps Gen Digital/Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate (generic), Gen Digital/AVG Antivirus Free, AVG Internet Security, AVG Ultimate (generic), Gen Digital/Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Gen Digital/Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate (generic), Gen Digital/AVG Antivirus Free, AVG Internet Security, AVG Ultimate (generic), Gen Digital/Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Gen Digital/Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimategeneric | * | Not reported |
| Gen Digital/AVG Antivirus Free, AVG Internet Security, AVG Ultimategeneric | * | Not reported |
| Gen Digital/Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advancedgeneric | * | Not reported |
Published upstream
Nov 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 6, 2026
An integer underflow vulnerability in the Avast Windows Filtering Platform (WFP) stream parser on Windows allows denial of service by causing a system crash. The WFP callout driver processes network stream data and computes length values for packet fragment reassembly. The length calculation does not properly validate input stream sizes against expected boundaries. When processing specially crafted input, the length computation underflows, resulting in allocation or buffer access with an extremely large wrapped-around size value. The underflow can be triggered remotely via network traffic destined for the filtered port, or locally via crafted data provided to the filtering interface. The resulting memory allocation failure or out-of-bounds access causes a kernel panic and system crash.
Quoted source text, attributed separately from HOL analysis.