Vulnerability in Apple Swift-Nio-Http2

CVE-2026-64785

SwiftNIO HTTP/2 was missing validation on inbound HEADERS frames that let CR, LF, NUL, SP and other control characters reach an HTTP/1.1 backend through NIOHTTP2's HTTP/2-to-HTTP/1 codec, enabling HTTP request smuggling or response splitting. This vulnerability is addressed in swift-nio-http2 version 1.45.0.

Vulnerability class: HTTP Request Smuggling

EPSS: 0.002 (7.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-64785?
CVE-2026-64785 is a medium-severity vulnerability in Apple Swift-Nio-Http2, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 5.3/10. Published 2026-07-23.
How severe is CVE-2026-64785?
Medium severity. CVSS v3 base score is 5.3 out of 10.