Buffer overflow in Avast Antivirus

CVE-2025-8351

Heap-based Buffer Overflow, Out-of-bounds Read vulnerability in Avira Antivirus engine when scanning a malformed file may allow Local Execution of Code or Denial-of-Service of the antivirus engine process. This issue affects Avira Antivirus on Windows, macOS, and Linux for engine builds before 8.3.70.98.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.002 (4.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 4.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-8351: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-8351?
CVE-2025-8351 is a high-severity vulnerability in Avast Antivirus, classified under Heap-based Buffer Overflow. CVSS score: 7.8/10. Published 2025-12-01.
How severe is CVE-2025-8351?
High severity. CVSS v3 base score is 7.8 out of 10.