SwiftNIO HTTP/2 (pre1.45.0) allows HTTP/1.1 request smuggling via control chars
CVE-2026-64785 Published on July 23, 2026
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 Analysis
CVE-2026-64785 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality, with no impact on integrity, and no impact on availability.
Weakness Type
What is a HTTP Request Smuggling Vulnerability?
When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.
CVE-2026-64785 has been classified to as a HTTP Request Smuggling vulnerability or weakness.
Products Associated with CVE-2026-64785
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Affected Versions
Apple swift-nio-http2:- Before 1.45.0 is affected.