Aswjsflt.dll in Avast Antivirus windows caused a crash of the Mozilla Firefox browser due to heap corruption

published 2022-12-07 3 y ago modified 2026-06-17 4 mo ago also EUVD-2022-51647

cvss: 7.7; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 39%
public exploits: 0; none known

The aswjsflt.dll library from Avast Antivirus windows contained a potentially exploitable heap corruption vulnerability that could enable an attacker to bypass the sandbox of the application it was loaded into, if applicable. This issue was fixed in version 18.0.1478 of the Script Shield Component.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 18 mo ago (2025-04-14)

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.7	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
NVD	3.1	10.0	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

NortonLifelock Avast Antivirus

Classification

Weakness

CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-787 Out-of-bounds Write

References

support.norton.com /sp/static/external/tools/security-advisories.html
vendor-advisory

Sources

CVE List CVE-2022-4291
NVD CVE-2022-4291

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Summary