CVE-2026-73314 XenForo < 2.3.13 Signature Verification Bypass via PayPal REST Webhook
Unauthenticated attackers can bypass PayPal webhook signature verification in XenForo, allowing them to process fabricated payment events.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-73314?
CVE-2026-73314 is a high-severity vulnerability in XenForo, published on 8 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-754
Which versions are affected by CVE-2026-73314?
It affects 1 product.
Products include Xenforo Xenforo.
How do I fix CVE-2026-73314?
No fix has been published for CVE-2026-73314 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-73314 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73314 exists.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in XenForo
- CVE-2025-71279 XenForo Passkey Security Bypass
- CVE-2026-73309 XenForo < 2.3.13 Authentication Bypass via OAuth2 Token Endpoint
- CVE-2026-73311 XenForo < 2.3.13 OAuth2 Authorization Code Reuse
- CVE-2026-73312 XenForo < 2.3.13 Refresh Token Replay via Expired Access Token
- CVE-2024-38457 Xenforo before 2.2.16 allows CSRF.
Sources
Also known as GHSA-rqwm-9m4j-f7g3.