CVE-2023-33999

Freemius SDK <= 2.5.9 - Reflected Cross-Site Scripting via fs_request_get

2023-07-18 00:00

Strategic Overview

Status: Patched in 2.8.3
Affected Plugin: Post Form – Registration Form – Profile Form for User Profiles – Frontend Content Forms for User Submissions (UGC)
Affected Version: <= 2.8.2
CVSS: 6.1Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2023-33999

View all Post Form – Registration Form – Profile Form for User Profiles – Frontend Content Forms for User Submissions (UGC) vulnerabilities

At a glance

CVE-2023-33999 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Post Form WordPress plugin, affecting versions <= 2.8.2. It carries a CVSS score of 6.1 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 2.8.3; sites on affected versions should update now. Disclosed July 2023, reported by Rafie Muhammad.

Vulnerability Overview

The Freemius SDK for WordPress is vulnerable to Reflected Cross-Site Scripting via the ‘fs_request_get’ function in versions up to, and including, 2.5.9 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.

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.

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

Post Form <= 2.8.2 carries this weakness at fs_request_get, and reaching it 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 Post Form the fix is 2.8.3: builds <= 2.8.2 are affected, anything from 2.8.3 onward is not.

Remediation

Update to version 2.8.3, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Post Form: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Post Form 2.8.3 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2023-33999 https://www.wordfence.com/threat-intel/vulnerabilities/id/5253fe2b-040b-417c-b257-0cb59ee5aa6e https://nvd.nist.gov/vuln/detail/CVE-2023-33999

Related records

Same weakness class

CVSS Vector

6.1

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone

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