CVE-2026-73314
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 38% of all known CVEs.
References
Related Vulnerabilities
Other CWE-754 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-4367 | High | 8.8 | 71% | - | Fix |
| CVE-2022-39288 | High | 7.5 | 59% | - | Fix |
| CVE-2023-30591 | High | 7.5 | 54% | - | - |
| CVE-2023-41993 | High | 8.8 | 29% | KEV | Fix |
| CVE-2024-43044 | High | 8.8 | 29% | - | Fix |
| CVE-2024-3393 | High | 7.5 | 28% | KEV | Fix |
Common questions
How do I fix CVE-2026-73314?
Upgrade xenforo to 2.3.13 or later.
Is CVE-2026-73314 being actively exploited?
Not that we know of. CVE-2026-73314 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.45% is the estimated probability that it will be exploited in the next 30 days. That is higher than 38% of all scored CVEs.
How severe is CVE-2026-73314?
CVE-2026-73314 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-73314 affect?
Published advisories record a fix for xenforo (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-11.