{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-80303","assignerOrgId":"dbd8429d-f261-4b1e-94cc-ae3132817e2e","state":"PUBLISHED","assignerShortName":"GEN","dateReserved":"2026-08-26T08:11:54.260Z","datePublished":"2026-11-06T15:59:24.348Z","dateUpdated":"2026-11-06T15:59:24.348Z"},"containers":{"cna":{"providerMetadata":{"orgId":"dbd8429d-f261-4b1e-94cc-ae3132817e2e","shortName":"GEN","dateUpdated":"2026-11-06T15:59:24.348Z"},"title":"Avast WFP stream parser integer underflow causes system crash","problemTypes":[{"descriptions":[{"lang":"en","cweId":"CWE-191","description":"CWE-191: Integer Underflow (Wrap or Wraparound)","type":"CWE"},{"lang":"en","cweId":"CWE-248","description":"CWE-248: Uncaught Exception","type":"CWE"}]}],"impacts":[{"descriptions":[{"lang":"en","value":"A local or remote attacker can trigger a system crash via denial of service by sending specially crafted network traffic that causes an integer underflow in the Windows Filtering Platform stream parser."}]}],"affected":[{"vendor":"Gen Digital","product":"Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate","platforms":["Windows"],"versions":[{"status":"affected","version":"0","lessThan":"26.7","versionType":"custom"}],"defaultStatus":"affected"},{"vendor":"Gen Digital","product":"AVG Antivirus Free, AVG Internet Security, AVG Ultimate","platforms":["Windows"],"versions":[{"status":"affected","version":"0","lessThan":"26.7","versionType":"custom"}],"defaultStatus":"affected"},{"vendor":"Gen Digital","product":"Norton Antivirus Plus, Norton 360 Standard, Norton 360 Deluxe, Norton 360 Advanced","platforms":["Windows"],"versions":[{"status":"affected","version":"0","lessThan":"26.7","versionType":"custom"}],"defaultStatus":"affected"}],"descriptions":[{"lang":"en","value":"An integer underflow vulnerability in the Avast Windows Filtering Platform (WFP) stream parser on Windows allows denial of service by causing a system crash.\n\n\n\nThe 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.\n\n\n\nThe 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.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>An integer underflow vulnerability in the Avast Windows Filtering Platform (WFP) stream parser on Windows allows denial of service by causing a system crash.</p><p>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.</p><p>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.</p>"}]}],"references":[{"url":"https://www.gendigital.com/us/en/contact-us/security-advisories/","name":"Gen Digital Security Advisories","tags":["vendor-advisory"]},{"url":"https://support.avast.com/en-us/article/Update-Antivirus","name":"Avast: how to update Avast Antivirus or Avast One","tags":["patch"]},{"url":"https://support.avg.com/SupportArticleView?l=en&urlname=Update-AVG-Antivirus","name":"AVG: updating AVG AntiVirus","tags":["patch"]},{"url":"https://support.norton.com/sp/en/us/home/current/solutions/v20240108175512167","name":"Norton: keep your Norton device security up to date","tags":["patch"]}],"solutions":[{"lang":"en","value":"Gen Digital has released a fix in Avast, AVG, and Norton version 26.7 and later. The fix adds input validation to the WFP stream parser length computation to detect and reject underflow conditions before they can result in memory allocation or access with invalid sizes.\n\n\n\nUpgrade to version 26.7 or later to remediate this issue.","supportingMedia":[{"type":"text/html","base64":false,"value":"<p>Gen Digital has released a fix in Avast, AVG, and Norton version <strong>26.7 and later</strong>. The fix adds input validation to the WFP stream parser length computation to detect and reject underflow conditions before they can result in memory allocation or access with invalid sizes.</p><p>Upgrade to version <strong>26.7 or later</strong> to remediate this issue.</p>"}]}],"credits":[{"lang":"en","value":"Teng Zheng Wang by VulnGuard Labs","type":"finder"}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"Vulnogram 1.0.5"}}}}