CVE-2020-4049

WordPress Core < 5.4.2 - Self-Cross Site Scripting via Theme Folder Name

2020-06-10 00:00
Nrimo Ing Pandum

Strategic Overview

Status
Patched in 3.7.34
Affected Core
WordPress 5.3
Affected Version
3.7 – 5.3.3 · 18 branches
CVSS
2.4Low
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2020-4049
View all WordPress 5.3 vulnerabilities

At a glance

CVE-2020-4049 is a low-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 2.4 (reachable over the network; low attack complexity). The issue is fixed in version 3.7.34; sites on affected versions should update now. Disclosed June 2020, reported by Nrimo Ing Pandum.

Vulnerability Overview

In affected versions of WordPress, when uploading themes, the name of the theme folder can be crafted in a way that could lead to JavaScript execution in /wp-admin on the themes page. This does require an admin to upload the theme, and is low severity self-XSS. 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.

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 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 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-2020-4049https://www.wordfence.com/threat-intel/vulnerabilities/id/92895f8e-59c9-4988-9d7a-2601880d71a2https://nvd.nist.gov/vuln/detail/CVE-2020-4049

Related records

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