What is CVE-2021-31988?

CVE-2021-31988 is a high-severity vulnerability in Axis OS, classified under CWE-1286. CVSS score: 8.8/10. Published 2021-10-05.

How severe is CVE-2021-31988?

High severity. CVSS v3 base score is 8.8 out of 10.

Vulnerability in Axis OS

CVE-2021-31988

A user controlled parameter related to SMTP test functionality is not correctly validated making it possible to add the Carriage Return and Line Feed (CRLF) control characters and include arbitrary SMTP headers in the generated test email.

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

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.010 (59.8th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 60th percentile — 59.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · 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)

References

www.axis.com/files/tech_notes/CVE-2021-31988.pdf (Vendor Advisory)

Frequently asked questions

What is CVE-2021-31988?: CVE-2021-31988 is a high-severity vulnerability in Axis OS, classified under CWE-1286. CVSS score: 8.8/10. Published 2021-10-05.
How severe is CVE-2021-31988?: High severity. CVSS v3 base score is 8.8 out of 10.