Instant CSS <= 1.1.4 - Missing Authorization via AJAX Actions
Strategic Overview
- Status
- Patched in 1.1.5
- Affected Plugin
- Instant CSS
- Affected Version
<= 1.1.4- CVSS
- 5.3Medium
- Weakness type
- CWE-862 · Missing Authorization
- CVE
CVE-2023-38483
At a glance
CVE-2023-38483 is a medium-severity Missing Authorization vulnerability in the Instant CSS WordPress plugin, affecting versions <= 1.1.4. It carries a CVSS score of 5.3 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 1.1.5; sites on affected versions should update now. Disclosed July 2023, reported by Abdi Pranata.
Vulnerability Overview
The Instant CSS plugin for WordPress is vulnerable to unauthorized access and modification of data due to missing capability checks on several functions called via AJAX actions in the ~/classes/class.instantcss_ajax.php file in versions up to, and including, 1.1.4. This makes it possible for authenticated attackers, with subscriber-level access and above, to perform a wide variety of actions such as retrieving css, theme, and minify data, along with updating the options for those. The unprotected AJAX actions present can be used to exploit a site via Cross-Site Scripting as well.
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, and no interaction from a victim user.
CWE-862: Missing Authorization
Reaching this weakness in Instant CSS <= 1.1.4 takes a caller who can reach the endpoint. A missing authorization check means a function is reachable by anyone who can reach the endpoint, because the code never asks whether the caller is allowed to perform the action.
Any user who can reach the endpoint gets to run an action reserved for higher-privileged roles, from reading protected data to changing settings or content. For Instant CSS the fix is 1.1.5: builds <= 1.1.4 are affected, anything from 1.1.5 onward is not.
Remediation
Update to version 1.1.5, 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: Instant CSS 1.1.5 closes this, and updating the plugin is the step that ends it.
- Login Security
- Alerts
External References
Related records
Other vulnerabilities in Instant CSS
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