CVE-2026-81741VulnerabilityPublished 09/09/2026

CVE-2026-81741: CWE-601 URL Redirection to Untrusted Site ('Open Redirect') in Groundhogg — CRM, Newsletters, and Marketing Automation

Affects Groundhogg — CRM, Newsletters, and Marketing AutomationSource CVE Database V5

ghsa-m96f-c5vh-h7cm

Not known to be exploited · CVSS 4.7 Medium.

Data as of 10/25/2026, 04:40:14 UTC

CVSS 3.1 base score

4.7Medium

How severe the flaw is on the 0–10 CVSS scale.

Exploitation: Not in CISA KEV, no exploitation reported
EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

What to do

Affected software

Product	Affected	Fixed in
Groundhogg — CRM, Newsletters, and Marketing Automation	Affected <4.7.2	Fixed in 4.7.2

AI-suggested

Until a patch is available, users should be cautious about links related to the email preference confirmation flow and consider implementing additional URL validation or filtering at the application or web server level.

Description

The Groundhogg — CRM, Newsletters, and Marketing Automation WordPress plugin before 4.7.2 does not restrict the redirect target of its email preference confirmation flow to the site's own host, allowing unauthenticated attackers to redirect visitors to an arbitrary external URL by way of a crafted link.

Impact

An attacker can use this vulnerability to redirect users to malicious external sites, potentially facilitating phishing or other social engineering attacks. There is no indication of direct compromise of the plugin or site beyond the redirect behavior.

Summary

The Groundhogg plugin prior to version 4.7.2 contains a CWE-601 URL redirection vulnerability. Specifically, the email preference confirmation flow fails to validate or restrict the redirect target to the same host, enabling open redirect attacks via crafted URLs. This vulnerability can be exploited without authentication.

Weaknesses

CWE-601URL Redirection to Untrusted Site ('Open Redirect') (opens in a new tab)
Base weaknessLikelihood of exploit: LowOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design
Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
Architecture and Design · Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
OWASP Cheat Sheets
Mass Assignment (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V5.1.5 (opens in a new tab)
Attack patterns
Cross-Site Flashing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

wpscan.com/vulnerability/4bfdee51-f2d0-4549-a9b4-5f4e11f2de4c/ (opens in a new tab)

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