What is CVE-2021-37453?

CVE-2021-37453 is a medium-severity vulnerability in Nchsoftware Axon Pbx, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-07-25.

How severe is CVE-2021-37453?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Nchsoftware Axon Pbx

CVE-2021-37453

Cross Site Scripting (XSS) exists in NCH Axon PBX v2.22 and earlier via the extension name (stored).

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-07-25 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (46.0th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 46.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Nchsoftware Axon Pbx

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.nch.com.au/pbx/index.html (Product)
github.com/0xfml/poc/blob/main/NCH/Axon_2.22_XSS.md (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-37453?: CVE-2021-37453 is a medium-severity vulnerability in Nchsoftware Axon Pbx, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-07-25.
How severe is CVE-2021-37453?: Medium severity. CVSS v3 base score is 5.4 out of 10.