CVE-2026-35054Network attack vector

Stored XSS via unsafe BB code rendering

Published Apr 1, 2026 · Updated Apr 1, 2026

Stored XSS in BB code rendering in XenForo 2.3.0 through 2.3.8 allows remote authenticated users to run script in viewers' browsers. The BB code renderer emits attacker-supplied script into generated page content instead of neutralizing it. Exploitation requires content-posting privileges and a viewer to load the stored content, exposing data and actions available in that viewer's session.

CVSS severity5.1
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in BB code rendering in XenForo 2.3.0 through 2.3.8 allows remote authenticated users to run script in viewers' browsers. The BB code renderer emits attacker-supplied script into generated page content instead of neutralizing it. Exploitation requires content-posting privileges and a viewer to load the stored content, exposing data and actions available in that viewer's session.

The record

CVE
CVE-2026-35054
Published
Apr 1, 2026
Updated
Apr 1, 2026
Vendor
XenForo Ltd.
Product
XenForo
Classifications
CWE-79, T1059.007
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 <2.3.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

XenForo Ltd. · XenForoversion=2.3.0 <2.3.9

Published CVSS scores

6.4VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
5.1VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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