XenForo up to 2.3.12 PayPal REST Webhook auth_algo signature verification

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.3$0-$5k0.82+

Summaryinfo

A vulnerability marked as problematic has been reported in XenForo up to 2.3.12. The affected element is an unknown function of the component PayPal REST Webhook Handler. This manipulation of the argument auth_algo causes signature verification. This vulnerability appears as CVE-2026-73314. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in XenForo up to 2.3.12. It has been declared as problematic. Affected by this vulnerability is an unknown code of the component PayPal REST Webhook Handler. The manipulation of the argument auth_algo with an unknown input leads to a signature verification vulnerability. The CWE definition for the vulnerability is CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. As an impact it is known to affect integrity. The summary by CVE is:

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.

It is possible to read the advisory at xenforo.com. This vulnerability is known as CVE-2026-73314 since 08/11/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 2.3.13 eliminates this vulnerability.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (VulnCheck): 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Signature verification
CWE: CWE-347 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: XenForo 2.3.13

Timelineinfo

08/11/2026 CVE reserved
09/08/2026 +28 days Advisory disclosed
09/08/2026 +0 days VulDB entry created
09/08/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: xenforo.com
Status: Confirmed

CVE: CVE-2026-73314 (🔒)
GCVE (CVE): GCVE-0-2026-73314
GCVE (VulDB): GCVE-100-399823

Entryinfo

Created: 09/08/2026 15:43
Changes: 09/08/2026 15:43 (75)
Complete: 🔍
Cache ID: 216::103

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