CVE-2021-33851

Customize Login Image <= 3.4 - Cross-Site Scripting

2021-12-02 00:00

Strategic Overview

Status: Patched in 3.5
Affected Plugin: Customize Login Image
Affected Version: <= 3.4
CVSS: 5.4Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2021-33851

View all Customize Login Image vulnerabilities

At a glance

CVE-2021-33851 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Customize Login Image WordPress plugin, affecting versions <= 3.4. It carries a CVSS score of 5.4 (reachable over the network; low attack complexity). The issue is fixed in version 3.5; sites on affected versions should update now. Disclosed December 2021, reported by Cyber Security Works Pvt. Ltd.

Vulnerability Overview

A cross-site scripting (XSS) attack can cause arbitrary code (JavaScript) to run in a user's browser and can use an application as the vehicle for the attack. The XSS payload given in the "Custom logo link" executes whenever the user opens the Settings Page of the "Customize Login Image" Plugin.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed.

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

Reaching this weakness in Customize Login Image <= 3.4 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 Customize Login Image the fix is 3.5: builds <= 3.4 are affected, anything from 3.5 onward is not.

Remediation

Update to version 3.5, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Customize Login Image: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Customize Login Image 3.5 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-33851 https://www.wordfence.com/threat-intel/vulnerabilities/id/1f9b02c1-2cd7-48ee-b568-4c42bc0ded96 https://nvd.nist.gov/vuln/detail/CVE-2021-33851

CVSS Vector

5.4

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

Base

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

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