CVE-2020-8599
CVE-2020-8599 is a security flaw in Trend Micro Apex One and OfficeScan, business antivirus software. Attackers can get into Trend Micro Apex One and OfficeScan without a valid password. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 3 Nov 2021.[1]
Trend Micro Apex One and OfficeScan is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff.
Description
CISA calls it an authentication bypass in Trend Micro Apex One and OfficeScan. In its words: “Trend Micro Apex One and OfficeScan server contain a vulnerable EXE file that could allow a remote attacker to write data to a path on affected installations and bypass root login.”[1]
The CVE record adds: “Trend Micro Apex One (2019) and OfficeScan XG server contain a vulnerable EXE file that could allow a remote attacker to write arbitrary data to an arbitrary path on affected installations and bypass ROOT login. Authentication is not required to exploit this vulnerability.”[2]
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it. CISA names the product as Trend Micro Apex One and OfficeScan.
Most families won’t have Trend Micro Apex One and OfficeScan; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 3 Nov 2021, 595 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 3 May 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 12%. That’s in the top 4% of the flaws it scores.[3]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Trend Micro Apex One and OfficeScan is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 3 May 2022 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 12%.[3] |
See also
Other Trend Micro Apex One and OfficeScan flaws
- CVE-2020-8467: remote code execution ·
Other Trend Micro flaws
- CVE-2026-34926, Trend Micro Apex One: (on-premise) directory traversal ·
- CVE-2025-54948, Trend Micro Apex One: OS command injection ·
- CVE-2023-41179, Trend Micro Apex One and Worry-Free Business Security: remote code execution ·
- CVE-2022-40139, Trend Micro Apex One and Apex One as a Service: improper validation ·
- CVE-2022-26871, Trend Micro Apex Central: arbitrary file upload ·
Similar flaws
- CVE-2026-102764, BeyondTrust Remote Support: authentication bypass by spoofing ·
- CVE-2025-61624, Fortinet products: path traversal ·
- CVE-2026-105133, AhsayCBS: improper authentication ·
- CVE-2015-3306, ProFTPD: improper access control ·
- CVE-2026-104286, Fortinet FortiMail: path traversal ·
Added the same day
- CVE-2021-42258, BQE BillQuick Web Suite: SQL injection ·
- CVE-2021-42013, Apache HTTP Server: path traversal ·
- CVE-2021-41773, Apache HTTP Server: path traversal ·
- CVE-2021-40539, Zoho ManageEngine: aDSelfService plus authentication bypass ·
- CVE-2021-40444, Microsoft MSHTML: remote code execution ·
Every Trend Micro flaw on CISA’s list · Everything added in November 2021
References
- ^ Cybersecurity and Infrastructure Security Agency. “Trend Micro Apex One and OfficeScan Authentication Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 3 Nov 2021.
- ^ National Institute of Standards and Technology. “CVE-2020-8599 Detail”. National Vulnerability Database, published 18 Mar 2020.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.119, percentile 96.1, 31 Oct 2026.
- CVE Program. “CVE-2020-8599”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.