What is CVE-2023-27397?

CVE-2023-27397 is a critical-severity vulnerability in Microengine Mailform, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2023-05-23.

How severe is CVE-2023-27397?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Arbitrary file upload in Microengine Mailform

CVE-2023-27397

Unrestricted upload of file with dangerous type exists in MicroEngine Mailform version 1.1.0 to 1.1.8. If the product's file upload function and server save option are enabled, a remote attacker may save an arbitrary file on the server and execute it.

Vulnerability class: Unrestricted File Upload

Published 2023-05-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (58.9th percentile), scored 2026-10-08.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Microengine Mailform
Microengine Inc. Mailform — versions version 1.1.0 to 1.1.8

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

References

microengine.jp/information/security_2023_05.html (Vendor Advisory)
jvn.jp/en/jp/JVN31701509/ (Third Party Advisory)

Frequently asked questions

What is CVE-2023-27397?: CVE-2023-27397 is a critical-severity vulnerability in Microengine Mailform, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2023-05-23.
How severe is CVE-2023-27397?: Critical severity. CVSS v3 base score is 9.8 out of 10.