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CVE-2026-80303

Avast WFP stream parser integer underflow causes system crash

No score

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.

Exploit likelihood

0.16%Scored on 2026-11-07. The trend appears after a second daily score.

What each source reports

CVE List No score

Avast WFP stream parser integer underflow causes system crash

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.

Record
CVE-2026-80303
Weakness
CWE-191, CWE-248
Updated
2026-11-06
EUVDEUVD-2026-118328 No score

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.

Record
EUVD-2026-118328
Updated
2026-11-06
GitHub AdvisoriesGHSA-2q9r-4cp6-374g No score

An integer underflow vulnerability in the Avast Windows Filtering Platform (WFP) stream parser on...

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.

Record
GHSA-2q9r-4cp6-374g
Weakness
CWE-191
Updated
2026-11-06
NVD No score

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.

Record
CVE-2026-80303
Weakness
CWE-191, CWE-248
Updated
2026-11-06

Affected products

History

History
RecordedChangedSources
publishedEUVD
publishedEUVD
aliases, referencesGitHub Advisories, NVD
cwes, references, titleCVE List
first indexedEUVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-80303 is a vulnerability with no CVSS score yet in Gen Digital Avast Antivirus, Avast One, Avast Premium Security, Avast Ultimate, published November 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.16%, the 4th percentile. No source names a fixed version.

References

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