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Xenforo CVE-2021-43032

MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2021-11-03 cve@mitre.org
4.8
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

CVSS score of 4.8 (MEDIUM). Attack characteristics: network attack vector, low complexity, high privileges required, user interaction required. Public proof-of-concept exploit code is available.

Exploit ScenarioDerived

A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.9% exploitation probability (EPSS)

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AnalysisAI

In XenForo through 2.2.7, a threat actor with access to the admin panel can create a new Advertisement via the Advertising function, and save an XSS payload in the body of the HTML document. Rated medium severity (CVSS 4.8), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. In XenForo through 2.2.7, a threat actor with access to the admin panel can create a new Advertisement via the Advertising function, and save an XSS payload in the body of the HTML document. This payload will execute globally on the client side. Affected products include: Xenforo. Version information: through 2.2.7.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 4.8 MEDIUM
AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

DescriptionNVD

In XenForo through 2.2.7, a threat actor with access to the admin panel can create a new Advertisement via the Advertising function, and save an XSS payload in the body of the HTML document. This payload will execute globally on the client side.

Threat Intelligence Overview

EPSS Score
0.9%
Top 45% exploitable
Exploit
POC
Public exploit code exists
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC Yes
EPSS 0.9%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

45
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +24
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

Affected Products (CPE)NVD

cpe:2.3:a:xenforo:xenforo:*:*:*:*:*:*:*:*
CVE-2024-38458 HIGH POC
8.8 Jun 16

Xenforo before 2.2.16 allows code injection. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable,

CVE-2024-38457 HIGH POC
8.8 Jun 16

Xenforo before 2.2.16 allows CSRF. Rated high severity (CVSS 8.8), this vulnerability is remotely exploitable, no authen

CVE-2025-71279 CRITICAL
9.3 Apr 01

Authentication bypass in XenForo versions prior to 2.3.7 compromises passkey-based authentication, allowing remote unaut

CVE-2026-73309 CRITICAL
9.1 Sep 08

Authentication bypass in XenForo before 2.3.13 lets unauthenticated attackers redeem a valid OAuth2 authorization code f

CVE-2026-73311 CRITICAL
9.1 Sep 08

OAuth2 authorization code replay in XenForo before 2.3.13 lets remote unauthenticated attackers redeem a previously used

CVE-2026-73312 CRITICAL
9.1 Sep 08

Analysis complete. The JSON synthesis is above. Two things worth flagging explicitly: 1. **Prompt injection ignored**

CVE-2026-73314 HIGH
8.7 Sep 08

Unauthenticated payment event forgery in XenForo before 2.3.13 stems from a logic error in the PayPal REST webhook signa

CVE-2026-73316 HIGH
8.7 Sep 08

Unauthorized subscription upgrades in XenForo before 2.3.13 are achievable by replaying valid PayPal REST webhook payloa

CVE-2026-74239 HIGH
8.6 Sep 08

Path traversal in XenForo's style archive importer on Windows deployments allows authenticated non-super administrators

CVE-2025-71281 HIGH
8.7 Apr 01

Remote code execution in XenForo versions before 2.3.7 allows authenticated users to invoke unauthorized methods through

CVE-2025-71278 HIGH
8.7 Apr 01

OAuth2 scope enforcement vulnerability in XenForo 2.3.x (prior to 2.3.5) allows authenticated client applications to req

CVE-2025-71282 HIGH
8.7 Apr 01

XenForo forum software versions prior to 2.3.7 disclose server filesystem paths through exception messages triggered by

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