CVE-2026-42551 Flight: HTTP method override enabled by default enables CSRF escalation and middleware bypass in flightphp/core
Flight PHP framework allows HTTP method override by default, enabling CSRF escalation and middleware bypass in GET requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42551?
CVE-2026-42551 is a high-severity vulnerability in flightphp core, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-436
Which versions are affected by CVE-2026-42551?
2 open source packages ship an affected version, including flightphp/core.
| Package | Affected | Fixed in |
|---|---|---|
flightphp/core Packagist | All versions | 3.18.1 |
flightphp/core Packagist | All versions | 3.18.1 |
How do I fix CVE-2026-42551?
Upgrade flightphp/core to 3.18.1 or later.
Is CVE-2026-42551 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42551 exists.
Sources
Also known as GHSA-vxrr-w42w-w76g.