CVE-2020-4047

WordPress Core < 5.4.2 - Authenticated Stored Cross-Site Scripting

2020-06-10 00:00
Luigi Gubello

Strategic Overview

Status
Patched in 3.7.34
Affected Core
WordPress 5.3
Affected Version
3.7 – 5.3.3 · 18 branches
CVSS
6.8Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2020-4047
View all WordPress 5.3 vulnerabilities

At a glance

CVE-2020-4047 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the WordPress 5.3 WordPress release line, affecting 3.7 – 5.3.3 · 18 branches. It carries a CVSS score of 6.8 (reachable over the network; low attack complexity; high integrity impact). Exploitation requires an authenticated account. The issue is fixed in version 3.7.34; sites on affected versions should update now. Disclosed June 2020, reported by Luigi Gubello.

Vulnerability Overview

In affected versions of WordPress, authenticated users with upload permissions (like authors) are able to inject JavaScript into some media file attachment pages in a certain way. This can lead to script execution in the context of a higher privileged user when the file is viewed by them. This has been patched in version 5.4.2, along with all the previously affected versions via a minor release (5.3.4, 5.2.7, 5.1.6, 5.0.10, 4.9.15, 4.8.14, 4.7.18, 4.6.19, 4.5.22, 4.4.23, 4.3.24, 4.2.28, 4.1.31, 4.0.31, 3.9.32, 3.8.34, 3.7.34).

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed. A successful exploit has high impact on integrity.

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

Reaching this weakness in WordPress 5.3 3.7 – 5.3.3 · 18 branches 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 WordPress 5.3 the fix is 3.7.34: builds 3.7 – 5.3.3 · 18 branches are affected, anything from 3.7.34 onward is not.

Remediation

Update to one of the following versions, or a newer patched version: 3.7.34, 3.8.34, 3.9.32, 4.0.31, 4.1.31, 4.2.28, 4.3.24, 4.4.23, 4.5.22, 4.6.19, 4.7.18, 4.8.14, 4.9.15, 5.0.10, 5.1.6, 5.2.7, 5.3.4, 5.4.2

How does WordSec protect against this?

The attempt arrives as an ordinary request to WordPress 5.3: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: updating to 3.7.34 is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2020-4047https://www.wordfence.com/threat-intel/vulnerabilities/id/371deb9d-707f-47e4-96d7-1a287926b536https://nvd.nist.gov/vuln/detail/CVE-2020-4047

Related records

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