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Noptin - Open Redirect (CVE-2021-25033)

CVE-2021-25033

Vulnerability CVE-2021-25033 PLUGIN noptin MEDIUM

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

CVE-2021-25033

MEDIUM CVSS 6.1 Published 2022-02-14 Updated 2026-06-17
AI Risk Moderate (53/100) Active Exploit: No strong signal Published Exploit: No public exploit references Priority: P4 Planned
Severity Band MEDIUM
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Affected Components 2
Reference Links 2
AI Risk Engine Moderate (53/100)
Exploitability Medium
Active Exploitation No strong signal
Published Exploit Status No public exploit references

Threat Timeline

  1. 2022-02-14 CVE published and first recorded in the threat feed.
  2. 2026-06-17 Record updated with latest vulnerability metadata.
  3. 2026-04-12 AI technical context refreshed for mitigation and impact guidance.
  4. Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated 176 days ago

AI enriched 176 days ago (2026-04-12 02:43 UTC)

Technical Summary

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

Potential Impact

Severity is MEDIUM (CVSS 6.1). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as Medium based on severity and technical exposure profile.

Primary risk drivers: severity and technical exposure profile

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

AI risk score 53/100 (Moderate, Medium) with priority P4 Planned. Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

Noptin PLUGIN · noptin Affected: < 1.6.5 Fixed in: 1.6.5
WordPress Newsletter Plugin PLUGIN · wordpress-newsletter Affected: < 1.6.5 Fixed in: 1.6.5

References

What to do about this

Patch on your next cycle Worth fixing, but not ahead of other work.

Fix it

Update Noptin to 1.6.5 or later.

That is the complete fix. Everything below is what protects you in the meantime.

Cannot update today? Request / payload inspection (WAF) in Hack Halt ProSecure blocks this class of attack before WordPress processes the request.

Inspect request parameters and bodies for injection, traversal and file-inclusion payloads, and refuse the request rather than logging it.

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Not sure if you are affected?

Scan your site to see whether it runs Noptin, and at which version.

Free, no installation, no account. It reads what your site already publishes, then tells you which plugins carry known vulnerabilities and what to do about each one.

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Am I affected by this vulnerability?

You are affected if your site runs Noptin. Versions below 1.6.5 are vulnerable; that release and later are not.

How do I fix it?

Update Noptin to version 1.6.5 or later. That is the complete fix. Until you can update, Request / payload inspection (WAF) in Hack Halt ProSecure contains this class of attack at the request layer.

What can an attacker actually do?

This is a Open Redirect flaw. An attacker who exploits it can use your domain to send visitors to a site they control.

WordPress security that blocks attacks before they land.

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