CVE-2026-64785 Apple CVE debrief

Who should care

Developers and administrators using SwiftNIO HTTP/2, especially those with exposure to untrusted or internet-facing HTTP/2 services, should review and apply the vendor patch. They should also verify and validate HTTP/2-to-HTTP/1 codec configurations, monitor for potential HTTP request smuggling or response splitting attacks, and update their inventory with affected SwiftNIO HTTP/2 versions. Security teams and vulnerability management teams should prioritize this vulnerability and track exceptions and retest remediated assets.

Technical summary

SwiftNIO HTTP/2 was missing validation on inbound HEADERS frames, allowing CR, LF, NUL, SP, and other control characters to reach an HTTP/1.1 backend through NIOHTTP2's HTTP/2-to-HTTP/1 codec. This enables HTTP request smuggling or response splitting attacks. Affected product context indicates potential risks to developers and administrators using SwiftNIO HTTP/2, especially those with exposure to untrusted or internet-facing HTTP/2 services.

Defensive priority

Medium-priority defensive review recommended due to potential HTTP request smuggling or response splitting risks.

Recommended defensive actions

• Review and apply vendor patch in swift-nio-http2 version 1.45.0
• Verify and validate HTTP/2-to-HTTP/1 codec configurations
• Monitor for potential HTTP request smuggling or response splitting attacks
• Update inventory with affected SwiftNIO HTTP/2 versions
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

Evidence from official CVE Program record and NIST NVD detail page indicates SwiftNIO HTTP/2 vulnerability allowing control characters to reach HTTP/1.1 backend. Vendor advisory and patch available. Affected product deployments should be reviewed for exposure, and owners assigned for follow-up. Compensating controls may be necessary while remediation is scheduled and verified.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.