What is CVE-2020-20118?

CVE-2020-20118 is a medium-severity vulnerability in Avast Antivirus, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 5.5/10. Published 2023-07-11.

How severe is CVE-2020-20118?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Buffer overflow in Avast Antivirus

CVE-2020-20118

Buffer Overflow vulnerability in Avast AntiVirus before v.19.7 allows a local attacker to cause a denial of service via a crafted request to the aswSnx.sys driver.

Vulnerability class: Buffer Overflow

Published 2023-07-11 · last modified 2026-07-09.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (5.1th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 5.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

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

Affected products

Avast Antivirus

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

af854a3a-2127-422b-91ae-364da2661108 (Vendor Advisory)
gitlab.com/yongchuank/avast-aswsnx-ioctl-82ac0060-oob-write (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2020-20118?: CVE-2020-20118 is a medium-severity vulnerability in Avast Antivirus, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 5.5/10. Published 2023-07-11.
How severe is CVE-2020-20118?: Medium severity. CVSS v3 base score is 5.5 out of 10.