flightphp core up to 3.18.0 GET Request Request::getMethod _method interpretation conflict

Summaryinfo

A vulnerability was found in flightphp core up to 3.18.0. It has been classified as problematic. This affects the function Request::getMethod of the component GET Request Handler. This manipulation of the argument _method causes interpretation conflict. The identification of this vulnerability is CVE-2026-42551. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in flightphp core up to 3.18.0 and classified as problematic. Affected by this vulnerability is the function Request::getMethod of the component GET Request Handler. The manipulation of the argument _method with an unknown input leads to a interpretation conflict vulnerability. The CWE definition for the vulnerability is CWE-436. Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state. As an impact it is known to affect integrity. The summary by CVE is:

Flight is an extensible micro-framework for PHP. Prior to 3.18.1, Request::getMethod() unconditionally honors the X-HTTP-Method-Override header and the $_REQUEST['_method'] parameter on any HTTP verb (including safe verbs such as GET), with no opt-in and no whitelist of permitted target methods. A GET request can silently become a DELETE or PUT, enabling CSRF escalation against destructive endpoints, bypass of middleware gated on unsafe verbs, and cache poisoning between CDN and origin. This vulnerability is fixed in 3.18.1.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-42551 since 04/28/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.18.1 eliminates this vulnerability.

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Productinfo

Vendor

• flightphp

Name

• core

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13
• 3.14
• 3.15
• 3.16
• 3.17
• 3.18.0

Website

• Product: https://github.com/flightphp/core/

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