CVE-2026-34926

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.

What this means for your business

It affects Trend Micro Apex One. It matters if your company, or a supplier that handles your data, runs it.
Attackers are already using it. CISA added it to its list of flaws used in real attacks on 21 May 2026.
FIRST's prediction model gives it a 13% chance of attack attempts being seen in the next 30 days, ranking above 96% of all known flaws.

What to do

1Check whether your company or your suppliers run Trend Micro Apex One.
2If you do, follow CISA's required action below. No patch reference has been published yet.
3Treat it as urgent. US federal agencies must fix it by 4 June 2026. That deadline does not apply to private companies, but it shows how seriously CISA takes it.
4Because attackers have used it, check the affected systems for signs of a break-in, not only for the update.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

Check if you’re exposed Book a call

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.

CISA’s wording, unedited.

Scoring

CVSS: Not yet scored

Dates

Published: 2026-05-21
Added to KEV: 2026-05-21
Remediation due: 2026-06-04
Sources: CISA KEV