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Meow Lightbox EUVDEUVD-2026-114574

| CVE-2026-109234 HIGH
Cross-site Scripting (XSS) (CWE-79)
2026-10-31 Wordfence GHSA-vv6j-8xxc-xhcc
7.2
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Identify site with Output Buffering/HtmlDomParser/Aggressive Resolve enabled
  2. Delivery
    Submit crafted img payload via anonymous bbPress reply
  3. Exploit
    Payload stored past kses allow-list
  4. Execution
    Plugin reprocesses HTML on render
  5. Persist
    Script executes in viewer's browser
  6. Impact
    Session/action abuse in victim context

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.

Exploitation Conditions

Exploitation is gated on a specific, stacked, non-default configuration that the attacker does not control: the administrator must have enabled Meow Lightbox's Output Buffering, selected the HtmlDomParser engine, and enabled Aggressive Resolve, AND the site must expose a stored-HTML submission surface (the description cites bbPress anonymous replies) whose kses allow-list still preserves img attributes. Given all of these, a single unauthenticated submission can store a payload that executes JavaScript when any user views the affected page. Limiting factors: the triple plugin-setting requirement plus a permissive kses img allow-list makes vulnerable deployments a minority; sites on default settings, without the HtmlDomParser/Aggressive Resolve path, or without an anonymous stored-HTML surface are not exploitable. Fixed in version 5.6.5.

Impact

The input CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N, score 7.2) portrays an easy, remote, unauthenticated stored-XSS, but the description sharply contradicts the AC:L assumption: exploitation requires the administrator to have simultaneously enabled Output Buffering, the HtmlDomParser engine, and Aggressive Resolve, AND to expose a stored-HTML submission surface (e.g. bbPress anonymous replies) whose kses allow-list still preserves img attributes. These are stacked non-default conditions beyond the attacker's control, so real-world attack complexity is high despite the AC:L in the supplied vector - this is the key signal conflict and defenders should weight it heavily. No EPSS score was provided; there is no CISA KEV listing and no public exploit was supplied (the references are the Wordfence advisory and source-code/changeset links, not exploit code). The vuln.today decision label is 'this_week', indicating a prioritized-but-not-emergency posture, consistent with a credible Wordfence-reported stored XSS that nonetheless depends on an uncommon configuration. Net: this is a legitimate issue to patch on a normal prioritized cadence rather than an emergency, because the headline 7.2/unauthenticated framing overstates ease relative to the config-dependent trigger the description actually requires.

Exploit ScenarioDerived

On a site where the administrator has enabled Meow Lightbox's Output Buffering, HtmlDomParser engine, and Aggressive Resolve, and where an anonymous stored-HTML surface such as bbPress anonymous replies passes img attributes through kses, an unauthenticated attacker submits a single crafted reply containing a malicious img payload. The plugin reprocesses the stored HTML on page render and the injected JavaScript then executes in the browser of any user who later views that page. No public exploit code was provided in the sources; the referenced links are the Wordfence advisory and source-code/changeset locations, not a weaponized PoC.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 31, 2026

Stored cross-site scripting in the Meow Lightbox WordPress plugin, affecting all versions up to and including 5.6.4, lets an unauthenticated attacker save a crafted payload that executes JavaScript in the browser of any user who later views the injected page. Exploitation is heavily gated: the administrator must have enabled Output Buffering, selected the HtmlDomParser engine and enabled Aggressive Resolve, and the site must additionally expose a stored-HTML submission surface (the description cites anonymous bbPress replies) whose kses allow-list still preserves img attributes. Where those conditions are met a single unauthenticated submission is sufficient; no public exploit code and no CISA KEV entry were identified at time of analysis, and the issue is fixed in version 5.6.5.

RemediationAI

Upgrade Meow Lightbox to version 5.6.5, which is the fixed release identified in the plugin Trac changeset (https://plugins.trac.wordpress.org/changeset?old_path=/meow-lightbox/tags/5.6.4&new_path=/meow-lightbox/tags/5.6.5); the Wordfence advisory at https://www.wordfence.com/threat-intel/vulnerabilities/id/45fcd17e-10d5-4357-84cc-2527b07b584e?source=cve is the vendor-related reference to track. If immediate update is not possible, remove the vulnerable configuration: turn off Output Buffering or switch away from the HtmlDomParser engine and disable Aggressive Resolve, accepting the loss of the lightbox's automatic DOM rewriting features, and/or close the stored-HTML submission surface by disabling anonymous bbPress replies and tightening the kses allow-list so img attributes are not preserved for untrusted submissions - noting that kses changes affect other legitimate embedded images. Sites on default settings, without the HtmlDomParser/Aggressive Resolve path, or without an anonymous stored-HTML surface are not exploitable, so confirming those settings is a useful triage step; the vendor identifies 5.6.5 as the complete fix.

Affected VersionsENISA

Meow Lightbox 0 ≤5.6.4

Affected Packages

euvd meow_lightbox no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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

Technical ContextAI · show details

Meow Lightbox is a WordPress plugin that rewrites image markup on rendered pages to drive its lightbox behaviour. In the affected path the plugin uses Output Buffering to capture the rendered page and passes that HTML through the vendored kub-at/php-simple-html-dom-parser library (simple_html_dom.php) as part of the Aggressive Resolve setting, so markup originating from user-submitted content is re-parsed and re-emitted into the page. The root cause is CWE-79: stored content that survives WordPress kses filtering with img attributes intact is neither sufficiently sanitized on input nor escaped on output when the DOM parser reconstructs the markup, allowing script to be injected into pages served to other users. The relevant sinks are visible in the plugin source referenced by the advisory (classes/core.php and the vendored parser). The vulnerable code path is only reached when the site owner has enabled Output Buffering, chosen the HtmlDomParser engine and turned on Aggressive Resolve, so this is a configuration-gated stored XSS rather than an unconditional one; consistent with that, our assessment rates the attack complexity as High (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N) even though the vendor-published vector uses AC:L.

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Severity by source

Vendor (Wordfence) PRIMARY HIGH
NVD 7.2 HIGH
AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
vuln.today AI 5.4 MEDIUM

Unauthenticated network submission (PR:N, AV:N), but the stacked non-default plugin settings and permissive kses allow-list are attacker-uncontrolled prerequisites, so AC:H; stored XSS in a victim browser gives S:C with C:L/I:L and no availability impact.

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

Primary rating from Vendor (Wordfence).

CVSS VectorNVD

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

DescriptionNVD

The Meow Lightbox plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'post_content (bbPress reply body)' parameter in all versions up to, and including, 5.6.4 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the administrator to have enabled Output Buffering, the HtmlDomParser engine, and Aggressive Resolve, as well as a stored-HTML submission surface (such as bbPress anonymous replies) whose kses allow-list preserves img attributes; given these preconditions, a one-shot unauthenticated submission can execute arbitrary JavaScript in the context of any user who views the affected page.

Executive ViewAI

Why It Matters

CVE-2026-109234 is a stored cross-site scripting vulnerability in the Meow Lightbox WordPress plugin, affecting all versions up to 5.6.4. Successful exploitation could allow an unauthenticated attacker to inject malicious scripts that execute in the browsers of users viewing affected pages, potentially leading to session hijacking or site defacement. However, exploitation is heavily dependent on specific, non-default plugin settings and an additional stored-HTML submission surface, making the likelihood of widespread exploitation low for most organizations.

Business Impact: Medium
Compensating Controls

Apply vendor patch (upgrade to version 5.6.5 or later). If patching is delayed, disable Output Buffering, switch to a different HTML parser engine, disable Aggressive Resolve, and restrict anonymous submissions to stored-HTML surfaces (e.g., disable anonymous bbPress replies) until the update can be applied.

Threat Intelligence Overview

EPSS Score
0.4%
Top 68% exploitable
Prevalence
Low
specific WordPress lightbox plugin, modest install base
Social Media
1
Sightings
Data Quality
4 sources
Confidence: Medium

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 HIGH
CISA KEV No
Public POC No
EPSS 0.4%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
Medium

Priority Score

36
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +36
PoC: 0
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.

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