CVE-2018-20979

Contact Form 7 <= 5.0.3 - Authorization Bypass

2018-09-04 00:00

Strategic Overview

Status: Patched in 5.0.4
Affected Plugin: Contact Form 7
Affected Version: < 5.0.4
CVSS: 6.3Medium
Weakness type: CWE-285 · Improper Authorization
CVE: CVE-2018-20979

At a glance

CVE-2018-20979 is a medium-severity Improper Authorization vulnerability in the Contact Form 7 WordPress plugin, affecting versions < 5.0.4. It carries a CVSS score of 6.3 (reachable over the network; low attack complexity). The issue is fixed in version 5.0.4; sites on affected versions should update now. Disclosed September 2018, reported by Simon Scannell.

Vulnerability Overview

The Contact Form 7 plugin for WordPress is vulnerable to authorization bypass due to capability_type mishandling in register_post_type in versions up to, and including, 5.0.3. This makes it possible for authenticated attackers with contributor level privileges and above to modify contact forms and potential supply paths to sensitive files that make sensitive information disclosure possible.

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.

CWE-285: Improper Authorization

Reaching this weakness in Contact Form 7 < 5.0.4 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 Contact Form 7 the fix is 5.0.4: builds < 5.0.4 are affected, anything from 5.0.4 onward is not.

Remediation

Update to version 5.0.4, or a newer patched version

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: Contact Form 7 5.0.4 closes this, and updating the plugin is the step that ends it.

Login Security
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2018-20979 https://www.wordfence.com/threat-intel/vulnerabilities/id/1814d2ad-73b1-4440-9cd6-7c5c569c4fb2 https://nvd.nist.gov/vuln/detail/CVE-2018-20979

Related records

Other vulnerabilities in Contact Form 7

CVSS Vector

6.3

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredLow
User InteractionNone
ScopeUnchanged
ConfidentialityLow
IntegrityLow
AvailabilityLow

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