CVE-2026-109997 kstover CVE debrief

Who should care

Defenders responsible for WordPress installations using the Ninja Forms plugin, version 3.15.5 or earlier, should assess exposure and prioritize verifying input sanitization and output escaping for the 'formData.extra' parameter.

Why it matters

CVE-2026-109997 is a Stored Cross-Site Scripting vulnerability in the Ninja Forms plugin for WordPress, allowing unauthenticated attackers to inject arbitrary web scripts. Defenders should prioritize verifying exposure and remediation due to the risk of unauthenticated attacks and potential script execution.

• Unauthenticated attackers can inject arbitrary web scripts in pages
• Injected scripts execute whenever a user accesses an injected page
• Defenders must verify input sanitization and output escaping for the 'formData.extra' parameter
• Remediation priority is high due to the risk of unauthenticated attacks

Technical summary

The Ninja Forms – Contact Form Builder with Calculators, Quizzes, Signatures & AI Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'formData.extra' parameter in all versions up to, and including, 3.15.5 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.

Defensive priority

Defenders should prioritize verifying exposure of WordPress installations using the Ninja Forms plugin, version 3.15.5 or earlier, and assess the risk of unauthenticated attackers injecting arbitrary web scripts.

Recommended defensive actions

• Verify WordPress installations for the Ninja Forms plugin, version 3.15.5 or earlier
• Assess the risk of unauthenticated attackers injecting arbitrary web scripts
• Prioritize input sanitization and output escaping for the 'formData.extra' parameter
• Consider upgrading to a patched version of the Ninja Forms plugin
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. However, the corpus does not establish versions beyond 3.15.5, exploitation, impact, or remediation, which require verification from the supplied official sources.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.