CVE-2026-34926
CVE-2026-34926 is a security flaw in Trend Micro Apex One, business antivirus software. Attackers can read files on Trend Micro Apex One that should be out of reach from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 21 May 2026.[1]
Trend Micro Apex One 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. Fixed in version 14.0.0.17079 and 14.0.20731.
Description
CISA calls it a (on-premise) directory traversal in Trend Micro Apex One. In its words: “Trend Micro Apex One (on-premise) contains a directory traversal vulnerability that could allow a pre-authenticated local attacker to modify a key table on the server to inject malicious code to deploy to agents on affected installations.”[1]
The CVE record adds: “A directory traversal vulnerability in the Apex One (on-premise) server could allow a pre-authenticated local attacker to modify a key table on the server to inject malicious code to deploy to agents on affected installations. This vulnerability is only exploitable on the on-premise version of Apex One and a potential attacker must have access to the Apex One Server and already obtained administrative credentials to the server via some other method to exploit this vulnerability.”[2]
The underlying weakness is CWE-23, in MITRE’s list of common software weaknesses.
It scores 6.7 out of 10 on the Common Vulnerability Scoring System, which rates it medium, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| TrendAI Apex One | 14.0.0.17079 |
| TrendAI Apex One as a Service | 14.0.20731 |
Most families won’t have Trend Micro Apex One; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 21 May 2026, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 4 Jun 2026 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 13%. That’s in the top 4% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Trend Micro has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Trend Micro Apex One 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 (fixed in version 14.0.0.17079 and 14.0.20731), or not in use. CISA gave US government agencies until 4 Jun 2026 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 6.7.[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 13%.[4] |
See also
Other Trend Micro Apex One flaws
- CVE-2025-54948: OS command injection ·
Other Trend Micro flaws
- 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 ·
- CVE-2021-36742, Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security: multiple products improper input validation ·
- CVE-2021-36741, Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security: multiple products improper input validation ·
Similar flaws
- CVE-2026-76519, Cisco Secure Email Gateway: relative path traversal ·
- CVE-2024-27199, JetBrains TeamCity: relative path traversal ·
- CVE-2025-64446, Fortinet FortiWeb: path traversal ·
- CVE-2022-37042, Synacor Zimbra Collaboration Suite (ZCS): authentication bypass ·
- CVE-2021-38163, SAP NetWeaver: unrestricted file upload ·
Added the same day
- CVE-2025-34291, Langflow: origin validation error ·
Every Trend Micro flaw on CISA’s list · Everything added in May 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Trend Micro Apex One (On-Premise) Directory Traversal Vulnerability”. Known Exploited Vulnerabilities Catalog, added 21 May 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-34926 Detail”. National Vulnerability Database, published 21 May 2026.
- ^ Trend Micro. Advisories and fixes: success.trendmicro.com, success.trendmicro.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.134, percentile 96.4, 31 Oct 2026.
- CVE Program. “CVE-2026-34926”. 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.