CVE-2017-6815

WordPress Core < 4.7.3 - Bypass URL Validation

2017-03-06 00:00

Strategic Overview

Status: Patched in 3.7.19
Affected Core: WordPress 4.7
Affected Version: 3.7 – 4.7.2 · 12 branches
CVSS: 6.1Medium
Weakness type: CWE-20 · Improper Input Validation
CVE: CVE-2017-6815

At a glance

CVE-2017-6815 is a medium-severity Improper Input Validation vulnerability in the WordPress 4.7 WordPress release line, affecting 3.7 – 4.7.2 · 12 branches. 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 3.7.19; sites on affected versions should update now. Disclosed March 2017, reported by Daniel Chatfield.

Vulnerability Overview

In WordPress before 4.7.3 (wp-includes/pluggable.php), control characters can trick redirect URL validation.

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-20: Improper Input Validation

Reaching this weakness in WordPress 4.7 3.7 – 4.7.2 · 12 branches takes a caller who can reach the endpoint. Improper input validation means the application accepts input without confirming it has the form, type or range the code downstream assumes.

The concrete impact depends on where the unvalidated value lands, which is why records in this class range from cosmetic bugs to full compromise. For WordPress 4.7 the fix is 3.7.19: builds 3.7 – 4.7.2 · 12 branches are affected, anything from 3.7.19 onward is not.

Remediation

Update to one of the following versions, or a newer patched version: 3.7.19, 3.8.19, 3.9.17, 4.0.16, 4.1.16, 4.2.13, 4.3.9, 4.4.8, 4.5.7, 4.6.4, 4.7.3

How does WordSec protect against this?

The attempt arrives as an ordinary request to WordPress 4.7: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: updating to 3.7.19 is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2017-6815 https://www.wordfence.com/threat-intel/vulnerabilities/id/0ed8ee65-d910-42a4-b6de-3229346dc59e https://nvd.nist.gov/vuln/detail/CVE-2017-6815

Related records

Same weakness class

Other vulnerabilities in WordPress 4.7

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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