StellarWP The Events Calendar Plugin up to 6.17.3 on WordPress Widget Classes parse_array classes code injection

Summaryinfo

A vulnerability was found in StellarWP The Events Calendar Plugin up to 6.17.3. It has been rated as critical. Impacted is the function Element_Classes::parse_array of the component Widget Classes. The manipulation of the argument classes leads to code injection. This vulnerability is uniquely identified as CVE-2026-78159. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, has been found in StellarWP The Events Calendar Plugin up to 6.17.3. This issue affects the function Element_Classes::parse_array of the component Widget Classes. The manipulation of the argument classes with an unknown input leads to a code injection vulnerability. Using CWE to declare the problem leads to CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

The The Events Calendar plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 6.17.3 via the parse_array function. This is due to insufficient validation of the widget 'classes' map, allowing a plain-array payload to bypass the is_safe_widget_instance() object check and reach the callable-invocation sink in Element_Classes::parse_array(). This makes it possible for unauthenticated attackers to execute code on the server. Exploitation requires that the targeted site has comments enabled on tribe_events posts and that at least one comment containing a crafted wp:legacy-widget block has been submitted, as the attack chain is triggered when do_blocks() processes the single-event HTML including the comment area.

It is possible to read the advisory at wordfence.com. The identification of this vulnerability is CVE-2026-78159 since 08/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/12/2026). The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• WordPress Plugin

Vendor

• StellarWP

Name

• The Events Calendar Plugin

Version

• 6.17.0
• 6.17.1
• 6.17.2
• 6.17.3

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CPE 2.2info

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