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CVE-2026-73314

XenForo < 2.3.13 Signature Verification Bypass via PayPal REST Webhook

Published: Sep 8, 2026Updated: Sep 11, 2026 Sources: CVE List NVDCWE-754
7.5HIGH
NVD MITRE
EPSS Score
0.5%
Top 61.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
Self-Check
Not available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-754

Affected Products

XenForo
commercialaka xenforo forum
XenForoOn-prem
Web & CMS Plugins / forum-wiki
and 1 more affected products View all →

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.
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References

https://bombobombone.github.io/posts/cve-2026-73314/
bombobombone.github.io
https://github.com/BomboBombone/CVE-2026-73314
github.com
https://www.vulncheck.com/advisories/xenforo-signature-verification-bypass-via-paypal-rest-webhook
vulncheck.com
and 2 more references View all →

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