phpMyAdmin up to 5.2.3 WebAuthn CustomServer.php parseAndValidateAssertionResponse assertion

Summaryinfo

A vulnerability classified as critical has been found in phpMyAdmin up to 5.2.3. This impacts the function CustomServer::parseAndValidateAssertionResponse of the file libraries/classes/WebAuthn/CustomServer.php of the component WebAuthn. The manipulation leads to assertion. This vulnerability is uniquely identified as CVE-2026-119561. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, has been found in phpMyAdmin up to 5.2.3. This issue affects the function CustomServer::parseAndValidateAssertionResponse of the file libraries/classes/WebAuthn/CustomServer.php of the component WebAuthn. The manipulation with an unknown input leads to a assertion vulnerability. Using CWE to declare the problem leads to CWE-617. The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

phpMyAdmin through 5.2.3 contains an authentication bypass vulnerability in CustomServer::parseAndValidateAssertionResponse() that never verifies WebAuthn assertion signatures against stored public keys. Attackers holding a victim's MySQL credentials can POST a crafted webauthn_request_response with matching challenge, origin, and rpIdHash to bypass the second factor and gain database privileges.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-119561 since 10/30/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 10/30/2026).

By approaching the search of inurl:libraries/classes/WebAuthn/CustomServer.php it is possible to find vulnerable targets with Google Hacking.

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

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Database Administration Software

Name

• phpMyAdmin

Version

• 5.2.0
• 5.2.1
• 5.2.2
• 5.2.3

License

• open-source

Website

• Product: https://www.phpmyadmin.net/

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