CVE-2020-36755

Customizr <= 4.3.0 - Cross-Site Request Forgery Bypass

2020-09-26 00:00

Strategic Overview

Status: Patched in 4.3.1
Affected Theme: Customizr
Affected Version: <= 4.3.0
CVSS: 4.3Medium
Weakness type: CWE-352 · Cross-Site Request Forgery (CSRF)
CVE: CVE-2020-36755

At a glance

CVE-2020-36755 is a medium-severity Cross-Site Request Forgery (CSRF) vulnerability in the Customizr WordPress theme, affecting versions <= 4.3.0. It carries a CVSS score of 4.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 4.3.1; sites on affected versions should update now. Disclosed September 2020, reported by Jerome Bruandet.

Vulnerability Overview

The Customizr theme for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 4.3.0. This is due to missing or incorrect nonce validation on the czr_fn_post_fields_save() function. This makes it possible for unauthenticated attackers to post fields via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

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-352: Cross-Site Request Forgery (CSRF)

Customizr <= 4.3.0 carries this weakness at czr_fn_post_fields_save(), and reaching it 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 Customizr the fix is 4.3.1: builds <= 4.3.0 are affected, anything from 4.3.1 onward is not.

Remediation

Update to version 4.3.1, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Customizr: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Customizr 4.3.1 closes this, and updating the theme is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2020-36755 https://www.wordfence.com/threat-intel/vulnerabilities/id/d9f6b600-a35a-49c2-8758-a7cc5c00e947 https://nvd.nist.gov/vuln/detail/CVE-2020-36755

Related records

Same weakness class

4.3CVE-2024-35771: Customizr <= 4.4.21 CSRF to Notice DismissalCVE-2024-35771

CVSS Vector

4.3

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityNone

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