CVE-2026-80303: Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate · Integer Underflow
Affects Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast UltimateSource CVE Database V5
Not known to be exploited.
Data as of 6 Nov 2026, 16:20 UTC
Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD
Thin evidence
One scorer or noneExploitation evidence
Disclosed: evidence found.
CVE published 6 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Gen DigitalAvast Antivirus, Avast One, Avast Premium Security, Avast Ultimate | Affected
| Fixed in– |
| Gen DigitalAVG Antivirus Free, AVG Internet Security, AVG Ultimate | Affected
| Fixed in– |
| Gen DigitalNorton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced | Affected
| Fixed in– |
AI-suggested
Users should monitor vendor advisories for updates. Until a fix is released, consider limiting exposure of the affected filtering interfaces to untrusted network traffic and avoid processing untrusted data through the affected components.
Description
CVE-2026-80303 is an integer underflow vulnerability in the Avast Windows Filtering Platform (WFP) stream parser on Windows. It allows denial of service by causing a system crash through improper length calculations during network stream processing. The vulnerability can be triggered remotely via network traffic or locally via crafted data, leading to kernel panic and system crash.
References
- gendigital.com/us/en/contact-us/security-advisories/ (opens in a new tab)
- support.avast.com/en-us/article/Update-Antivirus (opens in a new tab)
- support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus (opens in a new tab)
- support.norton.com/sp/en/us/home/current/solutions/v20240108175512167 (opens in a new tab)