The WPSpeed plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 2.6.10 This is due to a combination of two issues in the LightImages HTML optimizer: (1) Dispatcher::runOptimize() decides whether the current request is the site's home page by comparing only the URL path from REQUEST_URI against the path of the home URL, so on a plain-permalinks install the author archive URL /?author=<ID> is treated as the home page and the LightImages optimizer runs on it; and (2) LightImages::optimize() calls html_entity_decode() across the entire serialized DOMDocument output under the default-enabled img_processing_entity_decode setting, converting any entity-encoded markup present as plain text in the page (including WordPress's rendered author title) into live HTML

Attack Vector: Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

Attack Complexity: Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.

Privileges Required: Low

The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.

User Interaction: None

The vulnerable system can be exploited without any interaction from any user.

Scope: Changed

An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.

Confidentiality: Low

There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.

Integrity: Low

Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.

Availability: None

There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.