CVE-2021-40420
CVSS v3
8.8
HIGH
EPSS Score
4.7 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
A use-after-free vulnerability exists in the JavaScript engine of Foxit Software’s PDF Reader, version 11.1.0.52543. A specially-crafted PDF document can trigger the reuse of previously freed memory, which can lead to arbitrary code execution. An attacker needs to trick the user to open the malicious file to trigger this vulnerability. Exploitation is also possible if a user visits a specially-crafted, malicious site if the browser plugin extension is enabled.
Technical details
- Published
- 2022-02-04
Frequently asked questions
What is CVE-2021-40420?
A use-after-free vulnerability exists in the JavaScript engine of Foxit Software’s PDF Reader, version 11.1.0.52543. A specially-crafted PDF document can trigger the reuse of previously freed memory, which can lead to arbitrary code execution. An attacker needs to trick the user to open the malicious file to trigger this vulnerability. Exploitation is also possible if a user visits a specially-crafted, malicious site if the browser plugin extension is enabled.
Is CVE-2021-40420 actively exploited?
Active exploitation of CVE-2021-40420 has not been confirmed. Its EPSS score was 4.7% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-40420?
CVE-2021-40420 has a CVSS v3 base score of 8.8 (HIGH severity).
Is CVE-2021-40420 affecting your environment?
Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.
No credit card required · 500 free checks/month · Free API key
Other 2021 vulnerabilities worth triaging
Ranked by exploit probability (EPSS).