CVE-2016-6635

WordPress Core < 4.5 - Cross-Site Request Forgery via wp_ajax_wp_compression_test

2016-03-12 00:00

Strategic Overview

Status: Patched in 4.5
Affected Core: WordPress 4.5
Affected Version: < 4.5
CVSS: 8.8High
Weakness type: CWE-352 · Cross-Site Request Forgery (CSRF)
CVE: CVE-2016-6635

At a glance

CVE-2016-6635 is a high-severity Cross-Site Request Forgery (CSRF) vulnerability in the WordPress 4.5 WordPress release line, affecting < 4.5. It carries a CVSS score of 8.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 4.5; sites on affected versions should update now. Disclosed March 2016.

Vulnerability Overview

Cross-site request forgery (CSRF) vulnerability in the wp_ajax_wp_compression_test function in wp-admin/includes/ajax-actions.php in WordPress before 4.5 allows remote attackers to hijack the authentication of administrators for requests that change the script compression option.

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. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-352: Cross-Site Request Forgery (CSRF)

Reaching this weakness in WordPress 4.5 < 4.5 takes a caller who can reach the endpoint. Cross-site request forgery abuses the fact that browsers attach a victim's cookies to any request, so a state-changing action that only checks who you are, not whether you meant to act, can be triggered from another site.

An attacker who gets a logged-in user to load a crafted page can perform that action as them, with the impact scaling to whatever the victim's role is allowed to do. For WordPress 4.5 the fix is 4.5: builds < 4.5 are affected, anything from 4.5 onward is not.

Remediation

Update to version 4.5, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to WordPress 4.5: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: updating to 4.5 is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2016-6635 https://www.wordfence.com/threat-intel/vulnerabilities/id/0fbb1044-dd42-469d-9299-135ef2e609e0 https://nvd.nist.gov/vuln/detail/CVE-2016-6635

Related records

Same weakness class

Other vulnerabilities in WordPress 4.5

CVSS Vector

8.8

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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