CVE-2026-16145Network attack vectorHinoki check available

Unauthenticated stored XSS via captured action values

Published Aug 15, 2026 · Updated Aug 15, 2026

Stored XSS in Invisible Anti-Spam & CAPTCHA 5.1 and earlier allows remote attackers to inject scripts through the action parameter. The plugin records a matching action value and later places it in inline submit handlers without JavaScript-context escaping. An unauthenticated admin-ajax.php request is enough when its action matches an automatically populated explicit-actions entry; viewing the affected admin page executes the stored script.

CVSS severity7.2
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Stored XSS in Invisible Anti-Spam & CAPTCHA 5.1 and earlier allows remote attackers to inject scripts through the action parameter. The plugin records a matching action value and later places it in inline submit handlers without JavaScript-context escaping. An unauthenticated admin-ajax.php request is enough when its action matches an automatically populated explicit-actions entry; viewing the affected admin page executes the stored script.

The record

CVE
CVE-2026-16145
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
Matthias Nordwig
Product
Invisible Anti-Spam & CAPTCHA — reCAPTCHA Alternative for All Forms
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=5.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Matthias Nordwig · Invisible Anti-Spam & CAPTCHA — reCAPTCHA Alternative for All Formsversion=0 <=5.1

Published CVSS scores

7.2WordfenceCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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