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FlexStock EUVDEUVD-2026-114695

| CVE-2026-107711 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-10-31 Wordfence GHSA-2c44-25vc-hm3p
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
    Authenticate as Subscriber-level user
  2. Delivery
    Harvest exposed REST bearer token from Dashboard source
  3. Exploit
    Inject script via products[].post_content REST call
  4. Execution
    Payload stored on product page
  5. Impact
    Script executes in victim (admin) browser on 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.

Exploitation Conditions

Requires an authenticated Subscriber-level (or higher) account on a WordPress site with FlexStock ≤3.17.2 installed and active - practically low-barrier where customer self-registration is enabled, as is common on WooCommerce stores. No special plugin configuration is needed: the admin_enqueue_scripts callback unconditionally exposes the REST bearer token via wp_localize_script() in the Dashboard page source, and the REST endpoint's permission_callback checks only that bearer token rather than a current_user_can() capability check, so any logged-in Subscriber can reach the vulnerable products[].post_content write path. Limiting factors: an account is required (PR:L, not unauthenticated), and impact is realized only when another user subsequently views the injected page (stored payload, delayed execution).

Impact

This is a medium-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) reported by Wordfence. The signals are internally consistent: network-reachable (AV:N), low complexity (AC:L), scope change (S:C, reflecting script execution in another user's browser context), and low confidentiality/integrity impact with no availability impact. The key risk driver is the low privilege barrier (PR:L): the advisory states any Subscriber-level user can exploit it because the admin_enqueue_scripts callback leaks the REST bearer token in the Dashboard page source and the REST permission_callback validates only that token instead of calling current_user_can(). On WooCommerce stores with open customer/account registration, Subscriber access is trivially obtained, which effectively lowers the practical barrier. No EPSS score is present in the input and the CVE is not on CISA KEV, so there is no evidence of widespread or active exploitation; the vuln.today Decision label is 'this_month' (not act_now/emergency). No verified working exploit code is referenced - the links are the Wordfence advisory and plugin source lines, not a PoC. Net: a genuine but not emergency priority - patch on a routine monthly cycle, prioritized upward where self-registration is enabled. EPSS data is missing, so exploitation probability could not be weighed quantitatively.

Exploit ScenarioDerived

An attacker registers (or already holds) a Subscriber-level account on a WordPress store running FlexStock ≤3.17.2, then reads the REST bearer token exposed in the Dashboard page source and calls the plugin's REST endpoint to write a malicious script into a product's 'post_content'. The payload is stored and later executes in the browser of any user - including an administrator - who views the affected product page, enabling session/account compromise. No public exploit identified at time of analysis; only the vendor advisory and source-code references are provided.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 31, 2026

Stored cross-site scripting in the FlexStock - Product Stock Sync with Google Sheets for WooCommerce plugin affects every version through 3.17.2, letting a logged-in Subscriber-level user write arbitrary script into the products[].post_content field that later executes in the browser of anyone viewing the injected page. The low barrier is structural rather than a misconfiguration: the plugin's admin_enqueue_scripts callback prints the REST bearer token into the Dashboard page source via wp_localize_script() with no capability check, and the REST endpoint's permission_callback validates only that token instead of calling current_user_can(), so any Subscriber can reach the write path without plugin-specific setup. Wordfence reported it as a medium-severity issue (CVSS 6.4, CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N); no public exploit code and no confirmed active exploitation were identified at time of analysis, and priority is set to this month.

RemediationAI

The reference data points to an upstream fix in trunk rather than to a tagged patched release: changeset 3768111 modifies includes/models/class-product.php in the plugin's trunk (https://plugins.trac.wordpress.org/changeset/3768111/stock-sync-with-google-sheet-for-woocommerce/trunk/includes/models/class-product.php), so an upstream fix is available but a released patched version number is not independently confirmed here - check the plugin's changelog and update only once a build later than 3.17.2 is published, and treat a version number you cannot verify in the changelog as unpatched. If no patched build is available yet, deactivate the plugin until one ships; that removes both the token-disclosing admin_enqueue_scripts output and the vulnerable REST route, at the cost of losing Google Sheets stock synchronization. Because reachability requires only a Subscriber account, reducing who can obtain one - disabling open customer registration or gating new accounts on the store - lowers exposure while the plugin remains active, but it is not a complete fix: the bearer token is still exposed to every logged-in Subscriber and the endpoint still accepts it, so any account that exists remains a viable entry point. Review existing product content for injected markup after remediation, since stored payloads persist in the database until overwritten. Track the Wordfence advisory for the confirmed fixed version.

Affected VersionsENISA

FlexStock – Product Stock Sync with Google Sheets for WooCommerce 0 ≤3.17.2

Affected Packages

euvd flexstock_product_stock_sync_with_google_sheets_for_woocommerce 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 root cause class is CWE-79 (improper neutralization of input during web page generation), split across two weaknesses in the plugin's code path: the product model does not sanitize the products[].post_content value on write, and the value is later emitted without escaping. The privilege boundary that would normally keep this to administrators is broken by the REST layer - class-api.php registers an endpoint whose permission_callback trusts the bearer token alone rather than performing a capability check, while class-hooks.php registers an admin_enqueue_scripts callback that localizes that same token into the Dashboard page through wp_localize_script() for every logged-in user regardless of role. The result is that a Subscriber can obtain the token from page source and call the endpoint directly, reaching the product-content write path traced through class-product.php and class-app.php. Because the payload lands in stored product content, execution is deferred until another user views the affected page, which matches the CVSS scope-change rating (S:C) and the single low-integrity/low-confidentiality impact vector. The plugin stores WooCommerce product data synchronized against Google Sheets, so the affected records are ordinary storefront product entries rather than an isolated administrative-only surface.

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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

Subscriber account required so PR:L; network REST endpoint with no interaction (AV:N/AC:L/UI:N); stored script runs in other users' context so S:C with low C/I and no availability impact.

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:L/VI:L/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 FlexStock - Product Stock Sync with Google Sheets for WooCommerce plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'products[].post_content' parameter in all versions up to, and including, 3.17.2 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This is exploitable by any Subscriber-level user because the plugin's admin_enqueue_scripts callback exposes the REST bearer token in the Dashboard page source via wp_localize_script() without a capability check, and the REST endpoint's permission_callback validates only that bearer token rather than performing a current_user_can() capability check.

Threat Intelligence Overview

EPSS Score
0.3%
Top 72% exploitable
Prevalence
Low
niche wppool WooCommerce Google Sheets sync add-on, limited install base
Social Media
1
Sightings
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 0.3%
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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