How severe is CVE-2026-2428?

CVE-2026-2428 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-2428 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-2428?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-2428 have an EU (EUVD) identifier?

Yes. CVE-2026-2428 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8986.

When was CVE-2026-2428 published?

CVE-2026-2428 was published on 2026-02-27 and last updated on 2026-06-17.

CVE-2026-2428

CVE-2026-2428 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-345.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (4th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8986
Weakness: CWE-345
Published: 2026-02-27
Last modified: 2026-06-17

Description

The Fluent Forms Pro Add On Pack plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 6.1.17. This is due to the PayPal IPN (Instant Payment Notification) verification being disabled by default (`disable_ipn_verification` defaults to `'yes'` in `PayPalSettings.php`). This makes it possible for unauthenticated attackers to send forged PayPal IPN notifications to the publicly accessible IPN endpoint, marking unpaid form submissions as "paid" and triggering post-payment automation (emails, access grants, digital product delivery).

Frequently asked questions

What is CVE-2026-2428?: The Fluent Forms Pro Add On Pack plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 6.1.17. This is due to the PayPal IPN (Instant Payment Notification) verification being disabled by default (`disable_ipn_verification` defaults to `'yes'` in `PayPalSettings.php`). This makes it possible for unauthenticated attackers to send forged PayPal IPN notifications to the publicly accessible IPN endpoint, marking unpaid form submissions as "paid" and triggering post-payment automation (emails, access grants, digital product delivery).
How severe is CVE-2026-2428?: CVE-2026-2428 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-2428 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-2428?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-2428 have an EU (EUVD) identifier?: Yes. CVE-2026-2428 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8986.
When was CVE-2026-2428 published?: CVE-2026-2428 was published on 2026-02-27 and last updated on 2026-06-17.

References

Other CWE-345 (Insufficient Verification of Data Authenticity) vulnerabilities

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CVE-2022-36130 — Critical (CVSS 9.9): HashiCorp Boundary up to 0.10.1 did not properly perform data integrity checks to ensure the resources were associated…
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CVE-2025-15385 — Critical (CVSS 9.8): Insufficient Verification of Data Authenticity vulnerability in TECNO Mobile com.Afmobi.Boomplayer allows…

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