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CVE-2026-80303

Avast WFP stream parser integer underflow causes system crash

CVSS score

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EPSS probability

—

Risk score

—

Published

9 h ago

Official patch verified

Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.

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Vulnerability description

DayBreach AI Explanation

Verified against sources

CVE-2026-80303: Avast WFP Stream Parser Integer Underflow

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

CVE-2026-80303 is an integer underflow vulnerability in the Avast WFP stream parser on Windows. This flaw can lead to a system crash and denial of service.

Why does it matter?

This vulnerability allows attackers to trigger a kernel panic and system crash via network traffic or local data inputs, leading to a denial of service on targeted components.

What should be done?

  • Follow vendor advisories for product firmware or updates
  • Keep Avast Antivirus or Avast One up to date
  • Keep AVG AntiVirus and Norton device security up to date
Chain of evidence and sources2 verified claims

Avast Windows Filtering Platform akış ayrıştırıcısındaki tamsayı alt akışı, bir sistem çökmesine neden olabilir.

Zafiyet, filtrelenmiş porta gelen ağ trafiği veya filtreleme arayüzüne sağlanan yerel veriler aracılığıyla tetiklenebilir.

Show the technical text from the sources

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.

CWE: CWE-191, CWE-248

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-80303 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1Gen DigitalAvast Antivirus, Avast One, Avast Premium Security, Avast Ultimate View
2Gen DigitalAVG Antivirus Free, AVG Internet Security, AVG Ultimate View
3Gen DigitalNorton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced View
Total affected vendors: 1|Products: 3

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
The sources have not yet published a verified CVSS metric.

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

6 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

cvelist

Avast: how to update Avast Antivirus or Avast One

Open source
cvelist

AVG: updating AVG AntiVirus

Open source
cvelist

Norton: keep your Norton device security up to date

Open source
reference

Avast: how to update Avast Antivirus or Avast One

Open source
reference

AVG: updating AVG AntiVirus

Open source
reference

Norton: keep your Norton device security up to date

Open source
Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-80303 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-80303 weaknesses.

Official Sources and Advisories

Yama doğrulandı

6 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

Follow the vendor

Weakness Type (CWE & CAPEC)

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