Apple swift-nio-http2 up to 1.44.x HTTP/2 Codec response splitting

Summaryinfo

A vulnerability was found in Apple swift-nio-http2 up to 1.44.x and classified as critical. This vulnerability affects unknown code of the component HTTP2 Codec. Executing a manipulation can lead to response splitting. This vulnerability is tracked as CVE-2026-64785. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in Apple swift-nio-http2 up to 1.44.x and classified as critical. This vulnerability affects an unknown code of the component HTTP2 Codec. The manipulation with an unknown input leads to a response splitting vulnerability. The CWE definition for the vulnerability is CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. As an impact it is known to affect integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-64785 since 07/20/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/25/2026).

Upgrading to version 1.45.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-48369). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• Apple

Name

• swift-nio-http2

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25
• 1.26
• 1.27
• 1.28
• 1.29
• 1.30
• 1.31
• 1.32
• 1.33
• 1.34
• 1.35
• 1.36
• 1.37
• 1.38
• 1.39
• 1.40
• 1.41
• 1.42
• 1.43
• 1.44

License

• commercial

Website

• Vendor: https://www.apple.com/
• Product: https://github.com/apple/swift-nio-http2/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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