# CVE-2026-28975: Apple swift-nio-extras decompression ratio limit bypass in NIOHTTPRequestDecompressor

Source: https://junglewise.ai/threats/cve-2026-28975-apple-swift-nio-extras-decompression-ratio-limit-bypass-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-12. Updated: 2026-06-12  
License: CC BY 4.0 with a link back

CVE-2026-28975 · Severity: medium · CVSS 6.9 · Published 2026-06-12

A vulnerability in the Swift NIO Extras library allows attackers to bypass security limits designed to prevent 'zip bomb' attacks. By providing a fake size value in a web request, an attacker can force the server to decompress massive amounts of data, potentially crashing the service or exhausting its memory. This can lead to a denial-of-service (DoS) condition where the application becomes unavailable to legitimate users.

Vendors: [Apple](https://junglewise.ai/threats/vendors/apple), [Swift](https://junglewise.ai/threats/vendors/swift).

## Quick answers

**Is CVE-2026-28975 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-28975 being exploited in the wild.

**How severe is CVE-2026-28975?** Medium severity, with a CVSS score of 6.9, published 12 June 2026.

**Which products and versions are affected?** github.com/apple/swift-nio-extras (Swift) < 1.34.1.

**Is there a fix for CVE-2026-28975?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-28975 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-28975?** Check whether you run Apple SwiftNIO Extras or github.com/apple/swift-nio-extras (Swift) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The NIOHTTPRequestDecompressor component in swift-nio-extras fails to properly validate decompression ratios when configured with the .ratio(N) limit. The implementation relies on the attacker-controlled Content-Length header as the denominator for ratio calculations instead of the actual number of compressed bytes received. An attacker can exploit this by sending a highly compressed payload (gzip bomb) with an artificially inflated Content-Length header, causing the ratio check to always pass. This results in unbounded memory consumption during decompression. The vulnerability is fixed in version 1.34.1 by tracking actual received bytes.

## Affected products

- Apple swift-nio-extras < 1.34.1

## Identifiers

- CVE-2026-28975
- GHSA-6ph5-fww6-vfwv

## Timeline

- 2026-05-21: disclosed
- 2026-06-12: advisory

## References

- [https://api.github.com/users/nathanielmiller23](https://api.github.com/users/nathanielmiller23)
- [https://github.com/nathanielmiller23](https://github.com/nathanielmiller23)
- [https://api.github.com/users/nathanielmiller23/gists%7B/gist_id%7D](https://api.github.com/users/nathanielmiller23/gists%7B/gist_id%7D)
- [https://api.github.com/users/nathanielmiller23/repos](https://api.github.com/users/nathanielmiller23/repos)
- [https://avatars.githubusercontent.com/u/68157143?v=4](https://avatars.githubusercontent.com/u/68157143?v=4)
- [https://api.github.com/users/nathanielmiller23/events%7B/privacy%7D](https://api.github.com/users/nathanielmiller23/events%7B/privacy%7D)