CVE-2021-24838

AnyComment <= 0.3.4 - Open Redirect via redirect parameter

2021-12-20 00:00

Strategic Overview

Status: Patched in 0.3.5
Affected Plugin: AnyComment
Affected Version: < 0.3.5
CVSS: 5.4Medium
Weakness type: CWE-601 · URL Redirection to Untrusted Site ('Open Redirect')
CVE: CVE-2021-24838

At a glance

CVE-2021-24838 is a medium-severity URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the AnyComment WordPress plugin, affecting versions < 0.3.5. It carries a CVSS score of 5.4 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 0.3.5; sites on affected versions should update now. Disclosed December 2021, reported by Brandon James Roldan (tomorrowisnew).

Vulnerability Overview

The AnyComment plugin for WordPress is vulnerable to Open Redirect in versions up to, and including, 0.3.4. This is due to an API endpoint which passes user input via the redirect parameter to the wp_redirect() function without being validated first. This makes it possible for unauthenticated attackers to create redirect links using the site.

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-601: URL Redirection to Untrusted Site ('Open Redirect')

AnyComment < 0.3.5 carries this weakness at wp_redirect(), and reaching it takes a caller who can reach the endpoint. An open redirect is a page that takes a destination from the request and sends the browser there without checking that the destination belongs to the site.

A link that starts on a trusted domain finishes on an attacker's, which is what makes phishing and consent-screen abuse credible to the person clicking it. For AnyComment the fix is 0.3.5: builds < 0.3.5 are affected, anything from 0.3.5 onward is not.

Remediation

Update to version 0.3.5, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to AnyComment: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: AnyComment 0.3.5 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24838 https://www.wordfence.com/threat-intel/vulnerabilities/id/786d147b-2013-476b-a684-d070f07a166d https://nvd.nist.gov/vuln/detail/CVE-2021-24838

Related records

Other vulnerabilities in AnyComment

CVSS Vector

5.4

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

Base

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

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