Request smuggling via unvalidated HTTP/2 header values
Published Sep 18, 2026 · Updated Sep 18, 2026
HTTP request smuggling in Netty's HTTP/2 stack allows remote attackers to alter proxied traffic through crafted header values. DefaultHttp2Headers and DefaultHttp2HeadersDecoder leave value validation disabled, so NUL, LF, and CR pass through encoding and decoding unchanged. Exploitation requires an HTTP/2-to-HTTP/1.1 translation boundary with downstream validation disabled and can inject or split requests and responses.
Summary
What happened
HTTP request smuggling in Netty's HTTP/2 stack allows remote attackers to alter proxied traffic through crafted header values. DefaultHttp2Headers and DefaultHttp2HeadersDecoder leave value validation disabled, so NUL, LF, and CR pass through encoding and decoding unchanged. Exploitation requires an HTTP/2-to-HTTP/1.1 translation boundary with downstream validation disabled and can inject or split requests and responses.
The record
- CVE
- CVE-2026-93579
- Published
- Sep 18, 2026
- Updated
- Sep 18, 2026
- Vendor
- Commonhaus Foundation
- Product
- Red Hat AMQ Broker 7
- Classifications
- CWE-1035, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 18, 2026CVE publishedPublication date reported by the CVE source.
- Sep 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
- Netty prohibited-header conceptual proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Get started to see how Hinoki identifies affected software and validates exploitability in your environment.
Get started