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CVE-2026-73314 Details

Description

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.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:7.5 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://bombobombone.github.io/posts/cve-2026-73314/	[email protected]	ExploitThird Party Advisory
https://github.com/BomboBombone/CVE-2026-73314	[email protected]	ExploitThird Party Advisory
https://www.vulncheck.com/advisories/xenforo-signature-verification-bypass-via-paypal-rest-webhook	[email protected]	Third Party Advisory
https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/	[email protected]	Release Notes
https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/	[email protected]	Release Notes

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-754	Improper Check for Unusual or Exceptional Conditions	[email protected]

Affected Products

Product	Versions
xenforo xenforo	< 2.3.13
CPE cpe:2.3:a:xenforo:xenforo:::::::: Remediation No remediation found in references.

Change History

4 change records found show changes

Date	Action	Recorded By
Sep 11, 2026	Initial Analysis	[email protected]
Sep 10, 2026	CVE Modified	CISA-ADP
Sep 9, 2026	CVE Modified	[email protected]
Sep 8, 2026	New CVE Received	[email protected]