{"id":"CVE-2026-73314","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-73314","summary":"XenForo before 2.3.13 contains a signature verification logic error in the PayPal REST webhook handler that allows unauthenticated attackers to bypass payment signature validation by…","details":"XenForo before 2.3.13 contains a signature verification logic error in the PayPal REST webhook handler that allows unauthenticated attackers to bypass payment signature validation by submitting a webhook request with an unsupported auth_algo header value. When the algorithm cannot be mapped to a supported hash function, the verification function incorrectly returns true instead of failing, causing the caller to treat the fabricated request as verified and process the payment event without a valid PayPal signature.","published":"2026-09-08T14:17:25.640","modified":"2026-09-08T14:17:25.640","cvss":{"score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":null,"references":[{"type":"WEB","url":"https://www.vulncheck.com/advisories/xenforo-signature-verification-bypass-via-paypal-rest-webhook"},{"type":"WEB","url":"https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/"},{"type":"WEB","url":"https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/"}],"provenance":{"sources":["OSV.dev","NVD","FIRST.org (EPSS)"],"lastVerified":"2026-09-08T14:17:25.640"}}