themefic Ultra Addons for Contact Form 7 Plugin up to 3.5.54 on WordPress Extension Blocklist Gatekeeper cross site scripting

Summaryinfo

A vulnerability classified as problematic has been found in themefic Ultra Addons for Contact Form 7 Plugin up to 3.5.54. This impacts an unknown function of the component Extension Blocklist Gatekeeper. The manipulation leads to cross site scripting. This vulnerability is listed as CVE-2026-103999. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in themefic Ultra Addons for Contact Form 7 Plugin up to 3.5.54 and classified as problematic. This issue affects some unknown processing of the component Extension Blocklist Gatekeeper. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. The summary by CVE is:

The Ultra Addons for Contact Form 7 plugin for WordPress is vulnerable to Stored Cross-Site Scripting via File Upload in all versions up to, and including, 3.5.54 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The extension blocklist gatekeeper is bypassed by uploading text-type files (.txt, .csv, .vtt, .srt, .asc) whose contents begin with an HTML payload such as '<BODY onload=…>', as the check classifies these files as text/plain without inspecting their byte content.

The advisory is shared at wordfence.com. The identification of this vulnerability is CVE-2026-103999 since 10/01/2026. 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. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

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

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• WordPress Plugin

Vendor

• themefic

Name

• Ultra Addons for Contact Form 7 Plugin

Version

• 3.5.0
• 3.5.1
• 3.5.2
• 3.5.3
• 3.5.4
• 3.5.5
• 3.5.6
• 3.5.7
• 3.5.8
• 3.5.9
• 3.5.10
• 3.5.11
• 3.5.12
• 3.5.13
• 3.5.14
• 3.5.15
• 3.5.16
• 3.5.17
• 3.5.18
• 3.5.19
• 3.5.20
• 3.5.21
• 3.5.22
• 3.5.23
• 3.5.24
• 3.5.25
• 3.5.26
• 3.5.27
• 3.5.28
• 3.5.29
• 3.5.30
• 3.5.31
• 3.5.32
• 3.5.33
• 3.5.34
• 3.5.35
• 3.5.36
• 3.5.37
• 3.5.38
• 3.5.39
• 3.5.40
• 3.5.41
• 3.5.42
• 3.5.43
• 3.5.44
• 3.5.45
• 3.5.46
• 3.5.47
• 3.5.48
• 3.5.49
• 3.5.50
• 3.5.51
• 3.5.52
• 3.5.53
• 3.5.54

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