CVE-2026-64785: apple swift-nio-http2 HTTP Request/Response Smuggling

Vulnerability summary

CVE-2026-64785 is a medium (CVSS 5.3) HTTP Request/Response Smuggling vulnerability in apple swift-nio-http2. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 20% of scored vulnerabilities.

Timeline

1. 23-07-2026
   PublishedVulnerability first disclosed.
2. 24-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.