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WebberZone Top 10 CVE-2026-110290

| EUVDEUVD-2026-102790 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-10-16 Wordfence GHSA-x584-88mj-j8c7
6.4
CVSS 3.1 · Vendor: Wordfence
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Attack ChainAIDerived

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

  1. Access
    Obtain contributor-level account
  2. Delivery
    Craft Top 10 block with is_widget=1 JSON
  3. Exploit
    Inject payload into instance_id class attribute
  4. Execution
    Victim/admin views injected page
  5. Impact
    Script executes in their browser

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 requires an authenticated WordPress account with contributor-level privileges or above (PR:L) on a site running Top 10 - Popular Posts 4.5.2 or earlier. The attacker must set the undeclared 'is_widget' flag to '1' via block JSON, which activates the vulnerable code path in which the attacker-controlled 'instance_id' value is concatenated into an unescaped HTML class attribute. Payload execution additionally requires that another user (ideally a higher-privileged admin) subsequently accesses the page containing the injected block. Limiting factors: no unauthenticated access is possible, the site must permit contributor+ accounts (e.g., multi-author or open-registration blogs), and the attacker must deliberately construct the non-default is_widget block JSON - reducing realistic exposure for single-author sites.

Impact

This is a moderate-severity stored XSS (CVSS 6.4, CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N) that is a real but not urgent priority. The network attack vector and low complexity are offset by the PR:L requirement - a valid WordPress account with contributor-level access or above is needed, which meaningfully narrows the attacker pool to users who already have some authenticated foothold on the site. No EPSS score, KEV listing, or public POC was provided in the input, so there is no signal of active or widespread exploitation; this appears to be a Wordfence-reported research finding rather than an attacker-driven event. The scope change (S:C) and C:L/I:L impacts correctly reflect that injected script executes in the browsers of other users (including higher-privileged admins who view the affected page), which is the main value of the bug - potential privilege escalation via admin session compromise. Overall: a legitimate issue to patch, but it is a high-CVSS-relative-to-real-risk case where the contributor-access prerequisite limits exploitation to multi-author or open-registration sites. No signals conflict; the primary gap is the absence of EPSS/KEV/POC data, which is expected for a freshly disclosed plugin flaw.

Exploit ScenarioDerived

An attacker who has registered or obtained a contributor-level WordPress account crafts a Top 10 block whose JSON sets the undeclared is_widget flag to '1' and supplies a malicious instance_id value containing a script payload. When an administrator or other user later views the page containing that block, the unescaped class attribute executes the attacker's script in their browser, potentially hijacking the admin session. No public exploit code was identified at time of analysis, and the attack requires authenticated access rather than being remotely unauthenticated.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 16, 2026

Stored cross-site scripting (XSS) in the WebberZone Top 10 - Popular Posts WordPress plugin, a moderate-severity issue (CVSS 6.4), affects all versions up to and including 4.5.2 and allows an authenticated attacker with contributor-level privileges or higher to inject arbitrary web scripts via crafted block JSON. The attacker sets an undeclared is_widget flag to '1' and supplies a malicious instance_id value that is concatenated into an unescaped HTML class attribute, so the payload executes when a victim-potentially an administrator-views the injected page. No public exploit code has been identified at the time of analysis, and exploitation requires a WordPress site that permits contributor-level or higher accounts and a non-default block configuration.

RemediationAI

Vendor-released patch: update the WebberZone Top 10 - Popular Posts plugin to version 4.5.3 or later; the patched version is available from the WordPress plugin repository (see changeset 3747022 and the 4.5.3 tag). If immediate upgrade is not possible, disable or uninstall the plugin, though this removes the popular-posts functionality. Alternatively, restrict contributor-level and higher accounts to trusted users, since exploitation requires such privileges, and monitor for unauthorized block JSON modifications containing the is_widget flag or unusual class attributes. Sites with open registration or multi-author configurations should prioritize the upgrade, as the stored XSS can execute in an administrator's browser and lead to further compromise. Advisory: https://www.wordfence.com/threat-intel/vulnerabilities/id/4db4a201-a7fa-4764-87cb-c54b64adf560?source=cve

Affected VersionsENISA

WebberZone Top 10 — Popular Posts 0 ≤4.5.2

Affected Packages

euvd webberzone_top_10_popular_posts 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

The vulnerability is a stored XSS (CWE-79) caused by insufficient input sanitization and output escaping in the WordPress plugin's frontend display code. The plugin registers custom Gutenberg blocks (class-blocks.php), and helpers (class-helpers.php) parse block attributes including 'other_attributes' into an 'instance_id' value that is later used in class-display.php to construct an HTML class attribute. Normally the is_widget flag is not exposed to block JSON, but by injecting it as '1' in the block's JSON, an attacker activates a code path that concatenates the attacker-controlled instance_id directly into an unescaped class attribute. Because the malicious content is stored in post or page content, it persists and executes for any user who views the affected page. The affected component is identified by CPE cpe:2.3:a:ajay:webberzone_top_10_-_popular_posts:*:*:*:*:*:*:*:*. The CVSS vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N indicates network exploitable, low complexity, low privileges required, no user interaction once the page is visited, with scope change and limited confidentiality and integrity impact.

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Severity by source

Vendor (Wordfence) PRIMARY 6.4 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
vuln.today AI 6.4 MEDIUM

Contributor authentication required so PR:L; stored payload needs no victim interaction to inject (UI:N), executes across a scope boundary into other users' browsers (S:C) with limited C/I impact and no availability effect.

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

Primary rating from Vendor (Wordfence).

CVSS VectorVendor: Wordfence

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

DescriptionCVE.org

The WebberZone Top 10 - Popular Posts plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'other_attributes (parsed to inject instance_id) + undeclared is_widget' parameter in all versions up to, and including, 4.5.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The exploit requires setting the undeclared is_widget flag to '1' via block JSON, which activates the vulnerable code path that concatenates the attacker-controlled instance_id value into an unescaped HTML class attribute.

Threat Intelligence Overview

EPSS Score
0.2%
Top 90% exploitable
Prevalence
Low
niche WordPress popular-posts analytics plugin, modest install base
Data Quality
5 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 MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
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
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
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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