CVE-2026-42548

Flight: Reflected XSS via unvalidated JSONP callback in Flight::jsonp()

HIGH

8.6

CVSS Score

Published: May 13, 2026 at 07:21 PM UTC

Updated: October 26, 2026 at 02:10 PM UTC

1 product affected across 1 vendorFlight

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Severity

HIGH8.6

Exploit prediction

EPSS 0.4%

SSVC

PoC

Description

Flight is an extensible micro-framework for PHP. Prior to 3.18.1, Flight::jsonp() concatenates the ?jsonp= query parameter directly into an application/javascript response body without validating that the value is a legal JavaScript identifier. An attacker can inject arbitrary JavaScript that executes in the response origin, enabling reflected cross-site scripting. This vulnerability is fixed in 3.18.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Flight · Flightphpcomposer

90%

v < 3.18.1

Affected range stops below 3.18.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

x_refsource_CONFIRM

Source: cverecord

https://github.com/flightphp/core/security/advisories/GHSA-fcx8-ph5r-mxr4

SSVC — Action Prioritization

SSVCPoCAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.6HIGHGitHub_M

Vector?

Quick Info

StatusDEFERRED

CWE

CWE-79

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