{"id":"CVE-2026-73314","title":"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_…","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 submitting a webhook request with an unsupported auth_…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","cwe":["CWE-754"],"vendor":"xenforo","product":"xenforo","affected":["xenforo < 2.3.13"],"patched":["xenforo 2.3.13"],"published":"2026-09-08","updated":"2026-09-11","sourceUpdated":"2026-09-11T20:31:16.703","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-73314","references":[{"url":"https://bombobombone.github.io/posts/cve-2026-73314/","label":"disclosure@vulncheck.com"},{"url":"https://github.com/BomboBombone/CVE-2026-73314","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/xenforo-signature-verification-bypass-via-paypal-rest-webhook","label":"disclosure@vulncheck.com"},{"url":"https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/","label":"disclosure@vulncheck.com"},{"url":"https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/","label":"disclosure@vulncheck.com"}],"tags":["nvd","exploit-available","cve.org"],"epss":0.00651,"epssPercentile":0.49034,"exploits":{"github":1,"githubRepos":["https://github.com/BomboBombone/CVE-2026-73314"],"checkedAt":"2026-09-26T09:05:58.807Z"},"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"partial","timestamp":"2026-09-10T13:46:00.578050Z"},"ingestedAt":"2026-09-08T15:33:26.984Z","slug":"CVE-2026-73314","body":"## Overview\n\nXenForo 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.\n\n## Affected\n\n- `xenforo < 2.3.13`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `xenforo 2.3.13`","depth":"midnight","depthScore":53,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":8353,"id":"CVE-2026-73314","ts":1788920417364,"field":"exploit_available","old":"false","new":"true"}]}