CVE-2026-78187
Received Received - Intake

Cross-Site Scripting in Piwigo 16.3.0

Publication date: 2026-08-24

Last updated on: 2026-08-24

Assigner: VulDB

Description
A vulnerability has been found in Piwigo 16.3.0. This impacts an unknown function of the component Public Authentication Page. Such manipulation of the argument lang leads to cross site scripting. The attack may be performed from remote. A high complexity level is associated with this attack. The exploitability is said to be difficult. The exploit has been disclosed to the public and may be used. Upgrading to version 16.4.0 will fix this issue. The name of the patch is 5277a7dee4b8f1a174f1d69e1e2a4e1c82a3fc9e. It is recommended to upgrade the affected component.

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Meta Information

Published
2026-08-24
Last Modified
2026-08-24
Generated
2026-08-24
AI Q&A
2026-08-24
EPSS Evaluated
N/A
NVD
CVE-2026-78187
EUVD
EUVD-2026-64723

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
piwigo piwigo 16.3.0
piwigo piwigo 16.4.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
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.
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.

Attack-Flow Graph

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Executive Summary

CVE-2026-78187 is a reflected cross-site scripting (XSS) vulnerability in Piwigo version 16.3.0. It affects public authentication pages like identification.php, register.php, and password.php. The issue occurs when the user-controlled 'lang' cookie is not properly sanitized before being included in error messages. When an invalid 'lang' cookie value is provided, the application reflects this value directly into the HTML response without proper encoding, allowing an attacker to inject malicious JavaScript code.

Detection Guidance

To detect this vulnerability, check if your Piwigo instance is running version 16.3.0. Inspect the authentication pages (identification.php, register.php, password.php) for improper handling of the 'lang' cookie. Manually set a malicious 'lang' cookie with a payload like <script>alert(1)</script> and observe if it reflects in error responses without sanitization.

Impact Analysis

This vulnerability could allow an attacker to execute arbitrary JavaScript in your browser if they can manipulate the 'lang' cookie for the Piwigo origin. This may lead to phishing attacks, theft of session tokens or page content, unauthorized actions in your session, or data exfiltration. Exploitation requires the attacker to set the malicious cookie, which could involve techniques like cookie fixation or man-in-the-middle attacks.

Compliance Impact

This vulnerability could impact compliance with GDPR and HIPAA by enabling cross-site scripting (XSS) attacks. XSS may lead to unauthorized access to user data, session hijacking, or phishing attacks, which could violate data protection requirements under GDPR (e.g., Article 32 on security of processing) and HIPAA (e.g., safeguards for protected health information).

Mitigation Strategies

Upgrade Piwigo to version 16.4.0 or apply the patch 5277a7dee4b8f1a174f1d69e1e2a4e1c82a3fc9e. Ensure the 'lang' cookie is validated and sanitized using the new load_cookie_language() function to prevent XSS via error messages.

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