CVE-2026-11901 (CVSS 5.3)

Description

The WP Hotel Booking plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 2.3.1. This is due to the `web_hook_process_paypal_standard()` IPN handler selecting its PayPal validation endpoint from the attacker-controlled `$_REQUEST['test_ipn']` parameter, force-upgrading any `pending` transaction to `completed` when `test_ipn=1`, and omitting post-verification checks on `receiver_email`, `mc_currency`, and `txn_id` uniqueness after receiving a `VERIFIED` response from PayPal. This makes it possible for unauthenticated attackers to mark arbitrary hotel bookings as fully paid without submitting genuine payment to the merchant — either by routing IPN validation through PayPal's sandbox using a free sandbox account, or by replaying a previously verified IPN from a nominal payment to an attacker-controlled PayPal account. An attacker requires only a free PayPal sandbox account (or any PayPal account) to obtain a `VERIFIED` response; no site credentials or special configuration are needed.

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CVSS v3.1 Score

5.3

MEDIUM

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

EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-345 CWE-345

References

Other References

Frequently Asked Questions

What is CVE-2026-11901? +

The WP Hotel Booking plugin for WordPress is vulnerable to Insufficient Verification of Data Authenticity in all versions up to, and including, 2.3.1. This is due to the `web_hook_process_paypal_standard()` IPN handler selecting its PayPal validation endpoint from the attacker-controlled `$_REQUEST['test_ipn']` parameter, force-upgrading any `pending` transaction to `completed` when `test_ipn=1`, and omitting post-verification checks on `receiver_email`, `mc_currency`, and `txn_id` uniqueness after receiving a `VERIFIED` response from PayPal. This makes it possible for unauthenticated attackers to mark arbitrary hotel bookings as fully paid without submitting genuine payment to the merchant — either by routing IPN validation through PayPal's sandbox using a free sandbox account, or by replaying a previously verified IPN from a nominal payment to an attacker-controlled PayPal account. An attacker requires only a free PayPal sandbox account (or any PayPal account) to obtain a `VERIFIED` response; no site credentials or special configuration are needed. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-11901? +

CVE-2026-11901 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0018, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-11901? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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