CVE-2021-24533

Maintenance <= 4.02 - Authenticated Stored Cross-Site Scripting

2021-07-21 00:00

Strategic Overview

Status: Patched in 4.03
Affected Plugin: Maintenance
Affected Version: < 4.03
CVSS: 4.8Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2021-24533

At a glance

CVE-2021-24533 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Maintenance WordPress plugin, affecting versions < 4.03. It carries a CVSS score of 4.8 (reachable over the network; low attack complexity). Exploitation requires an authenticated account. The issue is fixed in version 4.03; sites on affected versions should update now. Disclosed July 2021, reported by Emil Kylander.

Vulnerability Overview

The Maintenance WordPress plugin before 4.03 does not sanitise or escape some of its settings, allowing high privilege users such as admin to se Cross-Site Scripting payload in them (even when the unfiltered_html capability is disallowed), which will be triggered in the frontend

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 Maintenance < 4.03 takes any authenticated account. 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 Maintenance the fix is 4.03: builds < 4.03 are affected, anything from 4.03 onward is not.

Remediation

Update to version 4.03, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Maintenance: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Maintenance 4.03 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24533 https://www.wordfence.com/threat-intel/vulnerabilities/id/c0dfa035-78fe-426f-a018-7bb2f22f0dd7 https://nvd.nist.gov/vuln/detail/CVE-2021-24533

CVSS Vector

4.8

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

Base

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

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