Vulnerability record · CVE-2026-73316 · published 8 September 2026

CVE-2026-73316: Xenforo insufficient verification of data authenticity vulnerability

Xenforo · Xenforo

XenForo before 2.3.13 contains a payment replay vulnerability in the PayPal REST payment provider that allows attackers to process the same webhook payload multiple times by exploiting a missing duplicate transaction ID check. Attackers can replay a valid webhook payload to trigger duplicate payment events, resulting in repeated subscription activations and unauthorized account upgrades.

8.7 CVSS 4.0 High EPSS 0.27% · top 83.5% CWE-345 · Insufficient verification of data authenticity

8.7CVSS 4.0 base score

0.27%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

5References, 2 tagged exploit

11 Sep 2026Last modified by NVD

Description

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Xenforo Xenforo

References

Link	Tags
https://bombobombone.github.io/posts/cve-2026-73316/	ExploitThird Party Advisory
https://github.com/BomboBombone/CVE-2026-73316	ExploitThird Party Advisory
https://www.vulncheck.com/advisories/xenforo-payment-replay-via-paypal-rest-payment-provider	Third Party Advisory
https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.23	Release Notes
https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/	Release Notes

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.3CVE-2025-71279Xenforo improper authentication vulnerabilityXenForo before 2.3.7 contains a security issue affecting Passkeys that have been added to user accounts. An attacker may be able to compromise the se…EPSS 0.45%1 Apr 2026 9.1CVE-2026-73311Xenforo authentication bypass by capture-replay vulnerabilityXenForo before 2.3.13 contains an OAuth2 authorization code reuse vulnerability that allows attackers to obtain unauthorized token pairs by submittin…EPSS 0.50%8 Sep 2026 9.1CVE-2026-73312Xenforo authentication bypass by capture-replay vulnerabilityXenForo before 2.3.13 contains a refresh token replay vulnerability that allows attackers to reuse a refresh token multiple times by exploiting the f…EPSS 0.47%8 Sep 2026 9.1CVE-2026-73309Xenforo vulnerabilityXenForo before 2.3.13 contains an authentication bypass vulnerability in the OAuth2 token endpoint that allows unauthenticated attackers to obtain va…EPSS 0.69%8 Sep 2026 8.8CVE-2024-38457Xenforo cross-site request forgery vulnerabilityXenforo before 2.2.16 allows CSRF.EPSS 7.4%16 Jun 2024 8.8CVE-2024-38458Xenforo code injection vulnerabilityXenforo before 2.2.16 allows code injection.EPSS 0.89%16 Jun 2024 8.7CVE-2026-73314Xenforo vulnerabilityXenForo before 2.3.13 contains a signature verification logic error in the PayPal REST webhook handler that allows unauthenticated attackers to bypas…EPSS 0.65%8 Sep 2026 8.7CVE-2025-71278Xenforo incorrect authorization vulnerabilityXenForo before 2.3.5 allows OAuth2 client applications to request unauthorized scopes. This affects any customer using OAuth2 clients on any version …EPSS 0.27%1 Apr 2026

Source: NIST National Vulnerability Database (record CVE-2026-73316), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.