CVE-2019-15838

Custom 404 Pro <= 3.2.7 - Reflected Cross-Site Scripting

2019-06-24 00:00

Strategic Overview

Status: Patched in 3.2.8
Affected Plugin: Custom 404 Pro
Affected Version: < 3.2.8
CVSS: 6.1Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2019-15838

At a glance

CVE-2019-15838 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Custom 404 Pro WordPress plugin, affecting versions < 3.2.8. It carries a CVSS score of 6.1 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 3.2.8; sites on affected versions should update now. Disclosed June 2019.

Vulnerability Overview

The custom-404-pro plugin before 3.2.8 for WordPress has reflected XSS, a different vulnerability than CVE-2019-14789.

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 privileges on the target site.

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

Reaching this weakness in Custom 404 Pro < 3.2.8 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 Custom 404 Pro the fix is 3.2.8: builds < 3.2.8 are affected, anything from 3.2.8 onward is not.

Remediation

Update to version 3.2.8, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Custom 404 Pro: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Custom 404 Pro 3.2.8 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2019-15838 https://www.wordfence.com/threat-intel/vulnerabilities/id/856f8b5f-809e-4ce2-8ef1-3ed169bc2b19 https://nvd.nist.gov/vuln/detail/CVE-2019-15838

Related records

Same weakness class

Other vulnerabilities in Custom 404 Pro

CVSS Vector

6.1

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

Base

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

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