CVE-2020-24557

CRITICALNVD 7.89.0
EchelonGraph scoreHIGH confidence

“▲” beside the score: it is higher than NVD's CVSS score.

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 7.8 retained for reference. The 9.0 is the floor for confirmed exploitation, not an impact rating: this CVE's impact severity (EG Severity) is CVSS 7.8 HIGH under GitHub Security Advisory CVSS. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: CISA Known Exploited Vulnerabilities catalog, EPSS, GitHub Security Advisory, NVD CVSS v3
Exploited in the wild

Also known asEUVD-2020-17276 (ENISA EUVD) · GHSA-rf37-cmcm-645m (GitHub Security Advisories)Source: ENISA EUVD

9.0EG
EchelonGraph verdictMitigate nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV) — the reason this is sooner than the SSVC decision on this page at low or medium mission impact
CISA-KEV: ExploitedEPSS PROB: 2.7%CVSS: 7.8Exploit: No code on recordExposed services: Not assessed

No fix has been recorded since the CVE record was published in 2020 — use a compensating control (WAF / firewall / segmentation) and check the vendor's advisory.

A vulnerability in Trend Micro Apex One and Worry-Free Business Security 10.0 SP1 on Microsoft Windows may allow an attacker to manipulate a particular product folder to disable the security temporarily, abuse a specific Windows function and attain privilege escalation. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. Please note that version 1909 (OS Build 18363.719) of Microsoft Windows 10 mitigates hard links, but previous versions are affected.

CVSS v3
7.8
EG Score
9.0CRITICALhigh confidence
EG Risk
75
EG Risk 75/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation100% × 40%
Fixed at 100% for a CISA KEV listing: EchelonGraph's rule.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Attend at medium and Act at high mission impact.
Exploitation active (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix has been recorded since the CVE record was published in 2020. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low, sooner than that at medium and as soon as possible at high mission impact.
EPSS PROB
2.7%
EPSS %ILE
85th
KEV
⚠ Exploited

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is the CISA KEV floor for confirmed exploitation, not an impact rating: its impact severity (EG Severity) is CVSS 7.8 HIGH.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
2.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
CISA KEV and EG-KEV Tier 1 (exploited in the wild)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Attend at medium mission impactTrack at low, Attend at medium and Act at high mission impact.CISA BOD 26-04: 3 days & forensic triage if the affected system is publicly exposed; 14 days if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: this CVE is in CISA's KEV catalog, and CISA's required action for it, quoted below, applies whether or not a fix is released.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Attend at medium and Act at high mission impact.

No fix has been recorded since the CVE record was published in 2020. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule at low, sooner than that at medium and as soon as possible at high mission impact.

Exploitation active (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days & forensic triage if the affected system is publicly exposed; 14 days if it is not.

No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: this CVE is in CISA's KEV catalog, and CISA's required action for it, quoted below, applies whether or not a fix is released.

The score's inputs: In CISA KEV yes (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

CISA required action“Apply updates per vendor instructions.”

Quoted verbatim from CISA's Known Exploited Vulnerabilities catalog. CISA directs it at US federal civilian executive branch agencies under Binding Operational Directive (BOD) 26-04, which replaced BOD 22-01 on 10 June 2026; it is not EchelonGraph's advice. CISA's notes: https://nvd.nist.gov/vuln/detail/CVE-2020-24557

Published

September 1, 2020

Last Modified

October 31, 2025

Advisory Details (4)

Auto-updated Nov 12, 2026
⚠️ Actively exploited (CISA KEV, CISA Vulnrichment). No fix on record since 2020. Sources: cisa.
CISA🔴 Active Exploitation

Known Exploited Vulnerabilities Catalog | CISA

Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-24557
Web page

ZDI-20-1094 - TrendAI™ Zero Day Initiative™ (ZDI)

https://www.zerodayinitiative.com/advisories/ZDI-20-1094/

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 57× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 1,214 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 1,114 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:38 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  2. 2026-11-12 22:23 UTCEchelonGraph re-scored
  3. 2026-11-12 22:23 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  4. 2026-11-12 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  5. 2026-11-11 20:13 UTCEchelonGraph re-scored
  6. 2026-11-11 20:13 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  7. 2026-11-11 16:30 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  8. 2026-11-10 18:03 UTCEchelonGraph re-scored
  9. 2026-11-10 18:03 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  10. 2026-11-10 16:34 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  11. 2026-11-09 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  12. 2026-11-09 15:55 UTCEchelonGraph re-scored
  13. 2026-11-09 15:55 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  14. 2026-11-08 16:31 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  15. 2026-11-08 13:47 UTCEchelonGraph re-scored
  16. 2026-11-08 13:47 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  17. 2026-11-07 16:33 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  18. 2026-11-07 11:38 UTCEchelonGraph re-scored
  19. 2026-11-07 11:38 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  20. 2026-11-06 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  21. 2026-11-06 09:30 UTCEchelonGraph re-scored
  22. 2026-11-06 09:30 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  23. 2026-11-05 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  24. 2026-11-05 07:22 UTCEchelonGraph re-scored
  25. 2026-11-05 07:22 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
Show 75 more
  1. 2026-11-04 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  2. 2026-11-04 05:14 UTCEchelonGraph re-scored
  3. 2026-11-04 05:14 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  4. 2026-11-03 16:36 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  5. 2026-11-03 03:06 UTCEchelonGraph re-scored
  6. 2026-11-03 03:05 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  7. 2026-11-02 16:36 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  8. 2026-11-02 00:56 UTCEchelonGraph re-scored
  9. 2026-11-02 00:56 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  10. 2026-11-01 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  11. 2026-10-31 22:48 UTCEchelonGraph re-scored
  12. 2026-10-31 22:48 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  13. 2026-10-31 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  14. 2026-10-30 20:40 UTCEchelonGraph re-scored
  15. 2026-10-30 20:40 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  16. 2026-10-30 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  17. 2026-10-29 18:32 UTCEchelonGraph re-scored
  18. 2026-10-29 18:32 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  19. 2026-10-29 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  20. 2026-10-28 16:27 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  21. 2026-10-28 16:25 UTCEchelonGraph re-scored
  22. 2026-10-28 16:24 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  23. 2026-10-27 16:27 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  24. 2026-10-27 14:16 UTCEchelonGraph re-scored
  25. 2026-10-27 14:16 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  26. 2026-10-26 16:27 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  27. 2026-10-26 12:08 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  28. 2026-10-25 18:46 UTCEchelonGraph re-scored
  29. 2026-10-25 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  30. 2026-10-25 10:00 UTCEchelonGraph re-scored
  31. 2026-10-25 10:00 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  32. 2026-10-24 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  33. 2026-10-24 07:51 UTCEchelonGraph re-scored
  34. 2026-10-24 07:51 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  35. 2026-10-23 16:27 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  36. 2026-10-23 05:40 UTCEchelonGraph re-scored
  37. 2026-10-23 05:40 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  38. 2026-10-22 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  39. 2026-10-22 03:32 UTCEchelonGraph re-scored
  40. 2026-10-22 03:32 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  41. 2026-10-21 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  42. 2026-10-21 01:24 UTCEchelonGraph re-scored
  43. 2026-10-21 01:23 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  44. 2026-10-20 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  45. 2026-10-19 23:13 UTCEchelonGraph re-scored
  46. 2026-10-19 23:13 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  47. 2026-10-19 16:27 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  48. 2026-10-18 21:05 UTCEchelonGraph re-scored
  49. 2026-10-18 21:05 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  50. 2026-10-18 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  51. 2026-10-18 09:28 UTCEchelonGraph re-scored
  52. 2026-10-17 18:56 UTCEchelonGraph re-scored
  53. 2026-10-17 18:56 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  54. 2026-10-17 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  55. 2026-10-16 16:45 UTCEchelonGraph re-scored
  56. 2026-10-16 16:45 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  57. 2026-10-16 16:33 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  58. 2026-10-15 16:27 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  59. 2026-10-15 14:34 UTCEchelonGraph re-scored
  60. 2026-10-15 14:34 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  61. 2026-10-14 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  62. 2026-10-14 12:26 UTCEchelonGraph re-scored
  63. 2026-10-14 12:25 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  64. 2026-10-13 16:28 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  65. 2026-10-13 10:15 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  66. 2026-10-12 19:40 UTCEchelonGraph re-scored
  67. 2026-10-12 16:29 UTCEPSS rescoreEPSS 2.7% · 85th percentile
  68. 2026-10-12 08:05 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  69. 2026-10-12 04:11 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  70. 2026-10-12 00:15 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  71. 2026-10-11 20:22 UTCEchelonGraph re-scored
  72. 2026-10-11 20:22 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  73. 2026-10-11 16:28 UTCEchelonGraph re-scored
  74. 2026-10-11 16:28 UTCGHSA enrichmentGHSA-rf37-cmcm-645m · GitHub severity HIGH · GitHub CVSS 7.8
  75. 2026-10-11 13:43 UTCEPSS rescoreEPSS 2.7% · 85th percentile

Frequently asked(6)

What is CVE-2020-24557?
CVE-2020-24557 is a critical-severity vulnerability; its CVE record was published on September 1, 2020. A vulnerability in Trend Micro Apex One and Worry-Free Business Security 10.0 SP1 on Microsoft Windows may allow an attacker to manipulate a particular product folder to disable the security temporarily, abuse a specific Windows function and attain privilege escalation. An attacker must first…
When was the CVE record for CVE-2020-24557 published?
The CVE record for CVE-2020-24557 was published on September 1, 2020. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 31, 2025; the record at its source may have been updated since.
Is CVE-2020-24557 actively exploited?
Yes. CISA added CVE-2020-24557 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Trend Micro Apex One, OfficeScan, and Worry-Free Business Security. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate attention. No fix has been recorded since the CVE record was published in 2020. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation.
What is the CVSS score of CVE-2020-24557?
CVE-2020-24557 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0 (CRITICAL).
Which products are affected by CVE-2020-24557?
CVE-2020-24557 affects Trend Micro Apex One, OfficeScan, and Worry-Free Business Security.
How do I remediate CVE-2020-24557?
No fix for CVE-2020-24557 has been recorded since its CVE record was published in 2020. Restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and check the vendor's advisory for a fix.

Dependency Blast Radius

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