CVE-2019-16780

WordPress Core < 5.3.1 - Stored Cross-Site Scripting via Block Editor

2019-12-13 00:00

Strategic Overview

Status: Patched in 3.7.32
Affected Core: WordPress 5.3
Affected Version: 3.7 – 5.3 · 18 branches
CVSS: 5.8Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2019-16780

At a glance

CVE-2019-16780 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 · 18 branches. It carries a CVSS score of 5.8 (reachable over the network; high confidentiality impact). The issue is fixed in version 3.7.32; sites on affected versions should update now. Disclosed December 2019, reported by Nguyen Van Khanh.

Vulnerability Overview

WordPress users with lower privileges (like contributors) can inject JavaScript code in the block editor using a specific payload, which is executed within the dashboard. This can lead to XSS if an admin opens the post in the editor. Execution of this attack does require an authenticated user. This has been patched in WordPress 5.3.1, along with all the previous WordPress versions from 3.7 to 5.3 via a minor release. Automatic updates are enabled by default for minor releases and we strongly recommend that you keep them enabled.

Technical Analysis

The vector marks this flaw as remotely reachable over the network. A successful exploit has high impact on confidentiality.

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

Reaching this weakness in WordPress 5.3 3.7 – 5.3 · 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 3.7.32: builds 3.7 – 5.3 · 18 branches are affected, anything from 3.7.32 onward is not.

Remediation

Update to one of the following versions, or a newer patched version: 3.7.32, 3.8.32, 3.9.30, 4.0.29, 4.1.29, 4.2.26, 4.3.22, 4.4.21, 4.5.20, 4.6.17, 4.7.16, 4.8.12, 4.9.13, 5.0.8, 5.1.4, 5.2.5, 5.3.1

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 3.7.32 is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2019-16780 https://www.wordfence.com/threat-intel/vulnerabilities/id/78b98f21-ac0c-496b-8cb9-8d2f3bd751b1 https://nvd.nist.gov/vuln/detail/CVE-2019-16780

Related records

Same weakness class

Other vulnerabilities in WordPress 5.3

CVSS Vector

5.8

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

Base

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredLow
User InteractionRequired
ScopeChanged
ConfidentialityHigh
IntegrityNone
AvailabilityNone

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