CVE-2020-24557: in the CISA KEV catalogue

Trend Micro Multiple Products Improper Access Control Vulnerability. CISA added CVE-2020-24557 to the Known Exploited Vulnerabilities catalogue on 2021-11-03 with a default due date of 2022-05-03. Known ransomware campaign use: Unknown. Forensic triage flag: No.

Trend Micro Apex One, OfficeScan, and Worry-Free Business Security on Microsoft Windows contain an improper access control vulnerability that may allow an attacker to manipulate a particular product folder to disable the security temporarily, abuse a specific Windows function, and attain privilege escalation. (CISA description)

Vendor / product: Trend Micro Apex One, OfficeScan, and Worry-Free Business Security
CWE: Not listed
CISA required action: Apply updates per vendor instructions.
EPSS: 2.7%, percentile 85 (scored 2026-11-03)

EPSS puts about 2.7 in 100 odds (2.7%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 85% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.

Vendor and reference links (from CISA)

https://nvd.nist.gov/vuln/detail/CVE-2020-24557

Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.

Data dates. CISA KEV catalogue version 2026.11.03, released 2026-11-03, 1,767 entries (checked 2026-11-03). EPSS model v2026.06.15, scored 2026-11-03, 399,388 CVEs. Sources: CISA and FIRST (EPSS by FIRST; scores generated by Empirical Security). Copied to our own database and refreshed automatically; if a refresh fails, the previous copy keeps serving with its own date.

Frequently asked questions

Is CVE-2020-24557 in the CISA KEV catalogue?

Yes. CISA added CVE-2020-24557 (Trend Micro Multiple Products Improper Access Control Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2021-11-03. CISA's default due date for it is 2022-05-03.

Is CVE-2020-24557 used in ransomware attacks?

CISA marks known ransomware campaign use as Unknown for CVE-2020-24557. That means CISA lacks confirmation, not that ransomware groups do not use it.

What should I do about CVE-2020-24557?

CISA's required action: Apply updates per vendor instructions.

Sources

CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
NVD record for CVE-2020-24557