CVE-2021-34620

WP Fluent Forms < 3.6.67 - Stored Cross-Site Scripting

2021-06-16 00:00

Strategic Overview

Status: Patched in 3.6.67
Affected Plugin: Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder
Affected Version: < 3.6.67
CVSS: 8.8High
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2021-34620

View all Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder vulnerabilities

At a glance

CVE-2021-34620 is a high-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Fluent Forms WordPress plugin, affecting versions < 3.6.67. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 3.6.67; sites on affected versions should update now. Disclosed June 2021, reported by Ram.

Vulnerability Overview

The WP Fluent Forms plugin < 3.6.67 for WordPress is vulnerable to Cross-Site Request Forgery leading to stored Cross-Site Scripting and limited Privilege Escalation due to a missing nonce check in the access control function for administrative AJAX actions

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Reaching this weakness in Fluent Forms < 3.6.67 takes a caller who can reach the endpoint. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Fluent Forms the fix is 3.6.67: builds < 3.6.67 are affected, anything from 3.6.67 onward is not.

Remediation

Update to version 3.6.67, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Fluent Forms: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Fluent Forms 3.6.67 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-34620 https://www.wordfence.com/threat-intel/vulnerabilities/id/8e039295-2ccf-450c-8f2a-d113117b9dce https://nvd.nist.gov/vuln/detail/CVE-2021-34620

Related records

Same weakness class

Other vulnerabilities in Fluent Forms – Customizable Contact Forms, Survey, Quiz, & Conversational Form Builder

CVSS Vector

8.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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