# CVE-2026-28898: SwiftNIO HTTP/2: HTTP/2-to-HTTP/1 Request Smuggling via unvalidated :path pseudo-header in HTTP2ToHTTP1Codec

> Attackers can inject control characters into HTTP/2 pseudo-headers, potentially causing HTTP request smuggling or response splitting in applications using swift-nio-http2.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jun 2026
- **Updated:** 25 Jun 2026
- **Also known as:** GHSA-4px2-pw77-vc85

## What is CVE-2026-28898?

CVE-2026-28898 is a medium-severity vulnerability in Apple swift-nio-http2, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

swift-nio-http2's HTTP/2-to-HTTP/1.1 codec did not validate pseudo-header values for control characters before placing them into the translated HTTP/1.1 message. swift-nio-http2 1.44.1 adds validation of all pseudo-header values (:path, :authority, :scheme, :method, and :status) at both the HPACK header validation layer and the HTTP/2-to-HTTP/1.1 translation layer. Requests or responses containing CR, LF, or NUL bytes in any pseudo-header value are now rejected with a connection error. This issue is fixed in swift-nio-http2 1.44.1.

Weakness: CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2026-28898?

2 open source packages ship an affected version, including github.com/apple/swift-nio-http2. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/apple/swift-nio-http2` | SwiftURL | All versions | 1.44.0 |
| `github.com/apple/swift-nio-http2` | SwiftURL | All versions | 1.44.0 |

Products: Apple Swiftnio Http\/2.

## How do I fix CVE-2026-28898?

Upgrade github.com/apple/swift-nio-http2 to 1.44.0 or later.

## Is CVE-2026-28898 being exploited?

There is no known exploitation of CVE-2026-28898 in the wild and no public exploit code.

## Other vulnerabilities in Apple swift-nio-http2

- [CVE-2022-0618](https://insights.sbomify.com/CVE-2022-0618/): Denial of service via HTTP/2 HEADERS frames padding (high 7.5)
- [CVE-2022-24666](https://insights.sbomify.com/CVE-2022-24666/): swift-nio-http2 vulnerable to denial of service via invalid HTTP/2 HEADERS frame length (high 7.5)
- [CVE-2022-24667](https://insights.sbomify.com/CVE-2022-24667/): swift-nio-http2 vulnerable to denial of service via mishandled HPACK variable length integer encoding (high 7.5)
- [CVE-2022-24668](https://insights.sbomify.com/CVE-2022-24668/): swift-nio-http2 vulnerable to denial of service via ALTSVC or ORIGIN frames (high 7.5)
- [CVE-2026-64785](https://insights.sbomify.com/CVE-2026-64785/): swift-nio-http2: Missing CR/LF/NUL validation in header values (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28898 and fix it if it is affected.

What it is: CVE-2026-28898 is a medium-severity vulnerability in Apple swift-nio-http2, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-28898 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/apple/swift-nio-http2 (SwiftURL): affected all versions; fixed in 1.44.0
- github.com/apple/swift-nio-http2 (SwiftURL): affected all versions; fixed in 1.44.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-28898/ (Markdown: https://insights.sbomify.com/CVE-2026-28898/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28898
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28898
- OSV: https://osv.dev/vulnerability/CVE-2026-28898

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28898/
Summaries are generated and may contain mistakes; the official description above is the record.