CVE-2021-25033Public exploitNetwork attack vector

User redirection via unvalidated destination parameter

Published Feb 14, 2022 · Updated Aug 3, 2024

Open redirect in Noptin before 1.6.5 allows remote attackers to redirect users to an attacker-chosen site through a crafted link. The public email-click route redirects the browser to the user-controlled to query parameter without validating its destination. Exploitation requires a user to follow the crafted URL; the redirect can support phishing but does not itself modify the WordPress site.

CVSS severity6.1
Medium
EPSS probability2.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Open redirect in Noptin before 1.6.5 allows remote attackers to redirect users to an attacker-chosen site through a crafted link. The public email-click route redirects the browser to the user-controlled to query parameter without validating its destination. Exploitation requires a user to follow the crafted URL; the redirect can support phishing but does not itself modify the WordPress site.

The record

CVE
CVE-2021-25033
Published
Feb 14, 2022
Updated
Aug 3, 2024
Vendor
Noptin Newsletter Team
Product
Noptin
Classifications
CWE-601, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.6.5 <1.6.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Noptin Newsletter Team · Noptinversion=1.6.5 <1.6.5

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
T1204.001User Execution: Malicious Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo