Is CVE-2026-42548 in the CISA KEV catalog?

No. CVE-2026-42548 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-42548?

CVE-2026-42548 has a CVSS v4 base score of 8.6 (HIGH).

What is the EPSS score for CVE-2026-42548?

CVE-2026-42548 has an EPSS score of 0.34% (26th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-42548

HIGH

8.6

CVSS v4

NVD

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.

CWE-79Cross-Site Scripting (XSS)

CVSS v4 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

Impact

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Exploit Intelligence

0.34%probability of exploitation in 30 days

26thpercentile

Low risk: more likely to be exploited than 26% of all known CVEs.

References

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

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.