What is CVE-2021-31987?

CVE-2021-31987 is a high-severity vulnerability in Axis OS, classified under CWE-1286. CVSS score: 7.5/10. Published 2021-10-05.

How severe is CVE-2021-31987?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Axis OS

CVE-2021-31987

A user controlled parameter related to SMTP test functionality is not correctly validated making it possible to bypass blocked network recipients.

Published 2021-10-05 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.9% 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

Axis OS
Axis OS 2016
Axis OS 2018
Axis OS 2020
Axis Communications Ab OS — versions AXIS OS 5.51 or later

Weakness classification (CWE)

CWE-1286

References

www.axis.com/files/tech_notes/CVE-2021-31987.pdf (Vendor Advisory)

Frequently asked questions

What is CVE-2021-31987?: CVE-2021-31987 is a high-severity vulnerability in Axis OS, classified under CWE-1286. CVSS score: 7.5/10. Published 2021-10-05.
How severe is CVE-2021-31987?: High severity. CVSS v3 base score is 7.5 out of 10.