Heap buffer out-of-bounds write vulnerability in Avast Antivirus when scanning a malformed...

Description

Heap buffer out-of-bounds write vulnerability in Avast Antivirus when scanning a malformed Windows PE file may allow Local Execution of Code or Denial-of-Service of the antivirus process.

This issue affects Avast Antivirus, AVG Antivirus, Norton Antivirus, Avast One, and Avast Business Antivirus on Windows, macOS, and Linux for virus definition builds before VPS 25040308.

The affected scanning logic is delivered through a shared Gen Digital virus definition update stream. The same stream feeds the consumer antivirus products listed in this advisory and other Gen Digital products that embed the same engine. Mitigation flows through this update channel; installations at or above the listed build are not vulnerable regardless of which product consumes the stream.

Basic information

Type
unreviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
Source code
Not specified
Published (advisory)
2026-06-13 00:34:30 UTC
Updated
2026-06-13 00:34:33 UTC
NVD published
2026-06-12

EPSS Score

Score Percentile
0.01% 3.20%

CVSS Scores

Base score Version Severity Vector
7.8 3.1
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

CWEs

CWE id Name
CWE-787 Out-of-bounds Write

References

cvelogic Threat Intelligence