What is CVE-2021-25033?

CVE-2021-25033 is a medium-severity vulnerability in Noptin, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2022-02-14.

How severe is CVE-2021-25033?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2021-25033 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Open Redirect in Noptin

CVE-2021-25033

The WordPress Newsletter Plugin WordPress plugin before 1.6.5 does not validate the to parameter before redirecting the user to its given value, leading to an open redirect issue

Vulnerability class: Open Redirect

Published 2022-02-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.023 (82.7th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 83rd percentile — 82.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.023 · newest: 0.023 · change: 0.000

Affected products

Noptin
WordPress Newsletter Plugin – Noptin — versions 1.6.5

Weakness classification (CWE)

CWE-601 — URL Redirection to Untrusted Site (Open Redirect)

Public proof-of-concept exploits

References

wpscan.com/vulnerability/c2d2384c-41b9-4aaf-b918-c1cfda58af5c (Exploit, Third Party Advisory)
plugins.trac.wordpress.org/changeset/2639592 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-25033?: CVE-2021-25033 is a medium-severity vulnerability in Noptin, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2022-02-14.
How severe is CVE-2021-25033?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2021-25033 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.