GHSA-q3g2-m552-3r9c

Suggest an improvement
Source
https://github.com/advisories/GHSA-q3g2-m552-3r9c
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-q3g2-m552-3r9c/GHSA-q3g2-m552-3r9c.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-q3g2-m552-3r9c
Aliases
  • CVE-2026-64785
Published
2026-07-24T21:52:10Z
Modified
2026-07-24T22:00:28.138171316Z
Severity
  • 5.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N CVSS Calculator
  • 6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
swift-nio-http2: Missing CR/LF/NUL validation in header values
Details

Summary

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.

Impact

Two related gaps in inbound header validation, against any application using HTTP2ToHTTP1Codec (or HTTP2FramePayloadToHTTP1Codec) to front an HTTP/1.1 backend:

Regular header field values were only checked against a forbidden-name list (connection, transfer-encoding, proxy-connection, keep-alive, upgrade); the value itself was never inspected. An attacker-controlled regular header field value containing CR or LF passed validation and, once serialized as name: value CRLF by the codec, terminated the field early and injected extra header lines into the outbound HTTP/1.1 message.

Pseudo-header values (:path in particular) were only checked against CR, LF and NUL. A :path value containing SP serializes into the request-target of METHOD SP request-target SP HTTP-version CRLF, so a value like /a HTTP/1.1 produces GET /a HTTP/1.1 HTTP/1.1 — a parser-differential request line depending on whether a downstream reader takes the first or last SP-delimited token as the version.

Neither of these is reachable on a stock pipeline: NIOHTTP1's outbound validator (enableOutboundHeaderValidation, on by default) already rejects these characters on write. The exposure is pipelines that skip outbound validation, or any code that reads validated-looking HTTPRequestHead.headers and forwards the values on trusting that HTTP/2 already checked them.

Fix

Fixed in 48bfd90 and 45bdf67.

Mitigation

Upgrade to 1.45.0

Database specific 
{
    "cwe_ids": [
        "CWE-113",
        "CWE-444"
    ],
    "github_reviewed_at": "2026-07-24T21:52:10Z",
    "severity": "MODERATE",
    "github_reviewed": true,
    "nvd_published_at": "2026-07-23T20:17:21Z"
}
References

Affected packages

SwiftURL / swift-nio-http2

Package

Name
swift-nio-http2
Purl
pkg:swift/swift-nio-http2

Affected ranges

Type
SEMVER
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.45.0

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-q3g2-m552-3r9c/GHSA-q3g2-m552-3r9c.json"