CVE-2021-24574

Simple Banner <= 2.10.3 - Authenticated (Admin+) Stored Cross-Site Scripting

2021-07-26 00:00

Strategic Overview

Status: Patched in 2.10.4
Affected Plugin: Simple Banner – Easily add multiple Banners/Bars/Notifications/Announcements to the top or bottom of your website
Affected Version: <= 2.10.3
CVSS: 5.5Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2021-24574

View all Simple Banner – Easily add multiple Banners/Bars/Notifications/Announcements to the top or bottom of your website vulnerabilities

At a glance

CVE-2021-24574 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Simple Banner WordPress plugin, affecting versions <= 2.10.3. It carries a CVSS score of 5.5 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Admin level or above. The issue is fixed in version 2.10.4; sites on affected versions should update now. Disclosed July 2021, reported by Asif Nawaz Minhas.

Vulnerability Overview

The Simple Banner WordPress plugin before 2.10.4 does not sanitise and escape one of its settings, allowing high privilege users such as admin to use Cross-Site Scripting payload even when the unfiltered_html capability is disallowed.

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 interaction from a victim user.

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

Reaching this weakness in Simple Banner <= 2.10.3 takes an account at Admin level or above. 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 Simple Banner the fix is 2.10.4: builds <= 2.10.3 are affected, anything from 2.10.4 onward is not.

Remediation

Update to version 2.10.4, or a newer patched version

How does WordSec protect against this?

An attacker needs Admin access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Simple Banner 2.10.4 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24574 https://www.wordfence.com/threat-intel/vulnerabilities/id/b890d168-9ea7-49c0-b628-71c76c0c2c9c https://nvd.nist.gov/vuln/detail/CVE-2021-24574

Related records

Same weakness class

Other vulnerabilities in Simple Banner – Easily add multiple Banners/Bars/Notifications/Announcements to the top or bottom of your website

4.4CVE-2024-12769: Simple Banner <= 3.0.3 Stored Cross-Site ScriptingCVE-2024-12769

CVSS Vector

5.5

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredHigh
User InteractionNone
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone

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