CVE-2018-20147

WordPress Core < 5.0.1 - Arbitrary File Deletion

2018-12-12 00:00

Strategic Overview

Status: Patched in 3.7.28
Affected Core: WordPress 5.0
Affected Version: 3.7 – 5.0 · 15 branches
CVSS: 7.7High
Weakness type: CWE-285 · Improper Authorization
CVE: CVE-2018-20147

At a glance

CVE-2018-20147 is a high-severity Improper Authorization vulnerability in the WordPress 5.0 WordPress release line, affecting 3.7 – 5.0 · 15 branches. It carries a CVSS score of 7.7 (reachable over the network; low attack complexity; high availability impact). The issue is fixed in version 3.7.28; sites on affected versions should update now. Disclosed December 2018, reported by Karim El Ouerghemmi.

Vulnerability Overview

In WordPress before 4.9.9 and 5.x before 5.0.1, authors could modify metadata to bypass intended restrictions on deleting files.

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 interaction from a victim user. A successful exploit has high impact on availability.

CWE-285: Improper Authorization

Reaching this weakness in WordPress 5.0 3.7 – 5.0 · 15 branches takes a caller who can reach the endpoint. Improper authorization means a permission check exists but does not cover the case being exercised, so a caller who is allowed to do one thing is allowed to do a neighbouring thing as well.

A lower-privileged account performs an action reserved for a higher one, which on a multi-author or membership site means an ordinary user reaching administrative behaviour. For WordPress 5.0 the fix is 3.7.28: builds 3.7 – 5.0 · 15 branches are affected, anything from 3.7.28 onward is not.

Remediation

Update to one of the following versions, or a newer patched version: 3.7.28, 3.8.28, 3.9.26, 4.0.25, 4.1.25, 4.2.22, 4.3.18, 4.4.17, 4.5.16, 4.6.13, 4.7.12, 4.8.8, 4.9.9, 5.0.1

How does WordSec protect against this?

Because it turns on account access, WordSec's login security is the relevant layer: role-based two-factor, captcha and brute-force limits raise the cost of getting the account this needs. None of that substitutes for the fix: updating to 3.7.28 is the step that ends it.

Login Security
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2018-20147 https://www.wordfence.com/threat-intel/vulnerabilities/id/7d61b06b-6709-4f60-8324-53775dbb3c04 https://nvd.nist.gov/vuln/detail/CVE-2018-20147

Related records

Same weakness class

Other vulnerabilities in WordPress 5.0

CVSS Vector

7.7

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredLow
User InteractionNone
ScopeChanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh

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