CVE-2025-71278Network attack vector

Expanded OAuth2 access via unauthorized scope requests

Published Apr 1, 2026 · Updated Apr 1, 2026

Incorrect authorization in XenForo before 2.3.5 allows remote authenticated users to obtain OAuth2 scopes not granted to their clients. XenForo has not disclosed the affected authorization locus or how requested scopes escape comparison with each client's allowed scope set. The flaw is reachable only when OAuth2 clients are configured and lets a client access API capabilities beyond its intended authorization.

CVSS severity8.7
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in XenForo before 2.3.5 allows remote authenticated users to obtain OAuth2 scopes not granted to their clients. XenForo has not disclosed the affected authorization locus or how requested scopes escape comparison with each client's allowed scope set. The flaw is reachable only when OAuth2 clients are configured and lets a client access API capabilities beyond its intended authorization.

The record

CVE
CVE-2025-71278
Published
Apr 1, 2026
Updated
Apr 1, 2026
Vendor
XenForo Ltd.
Product
XenForo
Classifications
CWE-863
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.3.0 <2.3.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

XenForo Ltd. · XenForoversion=2.3.0 <2.3.5

Published CVSS scores

8.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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