Cyber Resilience

CVE-2025-71278

Access Control in Xenforo 2.3.0 – 2.3.5

Public PoCAccess Control
Published
01 April 2026
Modified
01 April 2026
CVSS Score v4 8.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0027 18th percentile
Risk Priority 38 floored blend · peak EPSS

Summary

CVE-2025-71278 is a high-severity Incorrect Authorization (CWE-863) vulnerability in Xenforo Xenforo. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to AC-24 (Access Control Decisions) and AC-25 (Reference Monitor) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2025-71278 is a vulnerability in XenForo versions prior to 2.3.5 that allows OAuth2 client applications to request unauthorized scopes, violating the principle of incorrect authorization (CWE-863). This issue affects any XenForo 2.3 deployment utilizing OAuth2 clients, enabling those clients to potentially access resources beyond their intended authorization levels. The vulnerability carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating high severity due to its network accessibility, low attack complexity, and significant impacts on confidentiality, integrity, and availability.

An attacker with low privileges, such as a registered user able to register or control an OAuth2 client application, can exploit this vulnerability over the network without user interaction. By requesting excessive scopes during the OAuth2 authorization process, the attacker could gain elevated access to user data, administrative functions, or other protected resources, surpassing the permissions originally granted by the resource owner.

Advisories from VulnCheck and the official XenForo community announcement recommend upgrading to XenForo 2.3.5, which includes a security fix addressing the unauthorized scope requests in OAuth2 clients. Affected customers using OAuth2 integrations should apply this patch promptly to prevent exploitation.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

XenForo before 2.3.5 allows OAuth2 client applications to request unauthorized scopes. This affects any customer using OAuth2 clients on any version of XenForo 2.3 prior to 2.3.5, potentially allowing client applications to gain access beyond their intended authorization level.

CWE(s)
CWE-863

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1548 Abuse Elevation Control Mechanism Privilege Escalation
Adversaries may circumvent mechanisms designed to control privilege elevation to gain higher-level permissions.
attack.mitre.org →
T1548.002 Bypass User Account Control Privilege Escalation
Adversaries may bypass UAC mechanisms to elevate process privileges on system.
attack.mitre.org →
T1548.003 Sudo and Sudo Caching Privilege Escalation
Adversaries may perform sudo caching and/or use the sudoers file to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-71279Same product: Xenforo Xenforo
CVE-2024-38457Same product: Xenforo Xenforo
CVE-2024-25006Same product: Xenforo Xenforo
CVE-2024-38458Same product: Xenforo Xenforo
CVE-2026-35056Same product: Xenforo Xenforo
CVE-2025-71281Same product: Xenforo Xenforo
CVE-2026-35057Same product: Xenforo Xenforo
CVE-2026-35054Same product: Xenforo Xenforo
CVE-2026-35055Same product: Xenforo Xenforo
CVE-2025-71282Same product: Xenforo Xenforo

Affected Assets

xenforo
xenforo
2.3.0 — 2.3.5

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 5 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

AC-3 directly requires correct enforcement of authorization decisions on every access request, structurally preventing incorrect checks.

AC-24 Access Control Decisions good match

AC-24 ensures access-control decisions are made and applied consistently, reducing the chance of an incorrect authorization result.

AC-25 Reference Monitor good match

A reference monitor that is always invoked and tamper-proof forces every authorization decision through a verified, correct path.

AC-6 Least Privilege partial match

Least-privilege assignments shrink the set of authorizations that must be checked correctly, limiting exposure to flawed checks.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-05 mostly match
prevents

Defining, enforcing, and reviewing access authorizations and least privilege directly prevents incorrect authorization checks.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.15 Access control partial match
prevents

Requiring consistency between access rights and classification plus formal approval steps ensures that the authorization logic correctly distinguishes between entities that should and should not be granted access.

A.5.18 Access rights partial match
prevents

Enforcing policy-driven approval and role-change reviews stops incorrect or stale authorization decisions from remaining in effect after job changes or terminations.

A.8.3 Information access restriction partial match
prevents

By tying access rights to identity, device, location and classification, the control reduces the likelihood that an authorization decision will be based on an incorrect or bypassed policy.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248581 OL 8 must require users to provide a password for privilege escalation. prevents CWE-863
  • V-252656 The OL 8 operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-863
RHEL 7 (1 rule)
  • V-204430 The Red Hat Enterprise Linux operating system must be configured so that users must re-authenticate for privilege escalation. prevents CWE-863
RHEL 8 (1 rule)
  • V-251712 The RHEL 8 operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-863

References