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

mediumCVSS 5.3CVE-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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: medium — CVSS 5.3
Published: 2026-07-23
Last updated: 2026-07-24
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-64785

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-647850.18% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 8% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-64785	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

mediumGHSA-q3g2-m552-3r9c: swift-nio-http2: Missing CR/LF/NUL validation in header valuesghsa

Recent advisories for SwiftNIO HTTP/2 was

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumGHSA-4px2-pw77-vc85: SwiftNIO HTTP/2: HTTP/2-to-HTTP/1 Request Smuggling via unvalidated :path pseudo-header i…ghsa · 2026-06-12