CVE-2026-73316

EUVD-2026-72753
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7.5 HIGH
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 17.38%
Affected Products (NVD)
VendorProductVersion
xenforoxenforo
𝑥
< 2.3.13
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://bombobombone.github.io/posts/cve-2026-73316/
https://github.com/BomboBombone/CVE-2026-73316
https://www.vulncheck.com/advisories/xenforo-payment-replay-via-paypal-rest-payment-provider
https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/
https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/